ETSI TS 103 161-15 V1.1.1 (2011-10)

Access, Terminals, Transmission and Multiplexing (ATTM); Integrated Broadband Cable and Television Networks; IPCablecom 1.5; Part 15: Analog Trunking for PBX Specification

DTS/ATTM-003011-15

General Information

• Status: Published
• Publication Date: 26-Oct-2011
• Technical Committee: ATTM AT3 - Integrated broadband cable and television networks
• Current Stage: 12 - Completion
• Due Date: 31-Oct-2011
• Completion Date: 27-Oct-2011

Standards Content (Sample)

Technical Specification
Access, Terminals, Transmission and Multiplexing (ATTM);
Integrated Broadband Cable and Television Networks;
IPCablecom 1.5;
Part 15: Analog Trunking for PBX Specification

2 ETSI TS 103 161-15 V1.1.1 (2011-10)

Reference
DTS/ATTM-003011-15
Keywords
access, broadband, cable, IP, multimedia, PSTN
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3 ETSI TS 103 161-15 V1.1.1 (2011-10)
Contents
Intellectual Property Rights . 5
Foreword . 5
1 Scope . 7
1.1 Introduction and Purpose . 7
1.2 Relation to Other IPCablecom Specifications . 7
1.3 NCS Package Requirements . 8
2 References . 8
2.1 Normative references . 8
2.2 Informative references . 8
3 Definitions and abbreviations . 9
3.1 Definitions . 9
3.2 Abbreviations . 9
4 Void . 9
5 Overview . . 9
5.1 Functional Responsibility . 9
5.2 Physical Endpoint Interface . 10
5.2.1 Loop-Start Line Interface . 10
5.2.2 Ground-Start Line Interface . 10
5.2.3 DID PBX Trunk Interface . 10
5.2.4 E&M . 11
5.2.4.1 Two-wire E&M . 11
5.2.4.2 Four-wire E&M . 11
5.3 NCS Package Support . 11
6 Analog Trunking for PBX Functional Requirements . 12
6.1 Endpoint Configuration . 12
6.1.1 Physical Interface Type Configuration . 12
6.1.2 PBX Trunk Type Configuration . 13
6.1.3 Start of Dialling Method Configuration . 13
6.1.4 Out-pulse Dialling Method . 13
6.1.5 Maximum Out-pulsed Dial String Length . 13
6.1.6 Re-seizure Delay . 14
6.2 Signalling Support . 14
6.2.1 Digit and Digit Related Events . 15
6.2.2 Digit Events over E&M . 15
6.2.3 Local Tones . 15
6.2.3.1 Local Tones over E&M . 16
6.2.4 Caller ID and VMWI . 16
6.2.5 Hook Events. 16
6.2.6 Open Signal Interval . 16
6.2.7 Ring Requests . 17
6.2.8 T1 Trunk Signalling Requirements . 17
Annex A (normative): Event Packages . 18
A.1 IPCablecom Analog Trunking for PBX Package . 18
Annex B (informative): Sample Call Flows . 22
B.1 CALL SETUP Call Flow Example . 22
B.2 CALL TEARDOWN Call Flow Example . 27
B.3 CALL BLOCK/RELEASE Call Flow Example - Network Initiated . 29
B.4 CALL BLOCK/RELEASE Call Flow Example - PBX Initiated . 31
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4 ETSI TS 103 161-15 V1.1.1 (2011-10)
Annex C (informative): Bibliography . 34
History . 35

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5 ETSI TS 103 161-15 V1.1.1 (2011-10)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Specification (TS) has been produced by ETSI Technical Committee Access, Terminals, Transmission
and Multiplexing (ATTM).
The present document is part 15 of a multi-part IPCablecom 1.5 deliverable covering the Digital Broadband Cable
Access to the Public Telecommunications Network; IP Multimedia Time Critical Services, as identified below:
Part 1: "Overview";
Part 2: "Architectural framework for the delivery of time critical services over Cable Television Networks using
Cable Modems";
Part 3: "Audio Codec Requirements for the Provision of Bi-Directional Audio Service over Cable Television
Networks using Cable Modems";
Part 4: "Network Call Signalling Protocol";
Part 5: "Dynamic Quality of Service for the Provision of Real Time Services over Cable Television Networks
using Cable Modems";
Part 6: "Event Message Specification";
Part 7: "Media Terminal Adapter (MTA Management Information Base (MIB)";
Part 8: "Network Call Signalling (NCS) MIB Requirements";
Part 9: "Security";
Part 10: "Management Information Base (MIB) Framework";
Part 11: "Media terminal adapter (MTA) device provisioning";
Part 12: "Management Event Mechanism";
Part 13: "Trunking Gateway Control Protocol - MGCP option";
Part 14: "Embedded MTA Analog Interface and Powering Specification"
Part 15: "Analog Trunking for PBX Specification";
Part 16: "Signalling for Call Management Server";
Part 17: "CMS Subscriber Provisioning Specification";
Part 18: "Media Terminal Adapter Extension MIB";
Part 19: "IPCablecom Audio Server Protocol Specification - MGCP option";
Part 20: "Management Event MIB Specification";
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6 ETSI TS 103 161-15 V1.1.1 (2011-10)
Part 21: "Signalling Extension MIB Specification".
NOTE 1: Additional parts may be proposed and will be added to the list in future versions.
NOTE 2: The choice of a multi-part format for this deliverable is to facilitate maintenance and future
enhancements.
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7 ETSI TS 103 161-15 V1.1.1 (2011-10)
1 Scope
1.1 Introduction and Purpose
The present document defines extensions to the IPCablecom Network-based Call Signalling (NCS) [2] protocol to
support the following analogue trunking for PBX interfaces on an embedded Voice-Over-IP client device in a
IPCablecom environment:
• Ground-start lines.
• PBX one-way and two-way DTMF (dual-tone multi frequency tones) trunks.
As shown in figure 1, the IPCablecom NCS specification [2] already defines the Loop-Start line interface typically used
for residential services today. The present document is designed for additional line/trunk interfaces to support analogue
trunking for PBX so that the MTA (multimedia terminal adapter) may be used to interface directly to a Legacy PBX via
a Ground-Start line or other trunk interface (E&M - E and M Signalling or DID - Direct Inward Dialling). Example
PBX trunk interfaces are shown below.

Figure 1: Ground-Start Line and Loop Trunk Interfaces
1.2 Relation to Other IPCablecom Specifications
Analog Trunking for PBX is defined here as a supplement to the IPCablecom NCS interface. Though the present
document is included as part of the IPCablecom 1.5 release, the features specific to IPCablecom 1.5 are not required to
support analogue trunking for PBX. The capabilities defined in the present document may be supported by components
that conform to the IPCablecom 1.0 release. Full support for the IPCablecom 1.5 release is recommended for analogue
trunking for PBX due to the inclusion of additional features such as [5] and [4].
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8 ETSI TS 103 161-15 V1.1.1 (2011-10)
1.3 NCS Package Requirements
The IPCablecom analogue trunking (PAT) for PBX package is defined in the present document as an extension to the
NCS Line package to provide the needed functionality specific to analogue trunking for PBX. Both packages are
required to support analogue trunking for PBX. It should be noted that the PAT package is designed in such a way as to
provide a complete abstraction of the physical characteristics of an endpoint to the Call Agent. For example, the Call
Agent is unaware of the physical endpoint interface (e.g. E&M or DID), start of dialling method (e.g. wink start), and
out-pulse dialling type (e.g. DTMF). This abstraction exists due to time-to-market considerations. As such, the endpoint
is required to alter its behaviour based on these physical characteristics given a particular command from the Call
Agent. In some cases this behaviour breaks the general rules of NCS. The exceptions to NCS are documented in this
specification and apply only to analogue trunking for PBX.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
[1] ANSI T1.401: "Network to Customer Installations - Analog Voicegrade Switched Access Lines
Using Loop-Start and Ground-Start Signaling".
[2] ETSI TS 103 161-4: "Access, Terminals, Transmission and Multiplexing (ATTM); Integrated
Broadband Cable and Television Networks; IPCablecom 1.5; Part 4: Network Call Signalling
Protocol".".
[3] TIA-464-C: "Requirements for Private Branch Exchange (PBX) Switching Equipment".
[4] IETF RFC 2833: "RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals", May
2000.
[5] ITU-T Recommendation T.38: "Procedures for real-time group 3 facsimile communication over IP
networks", September 2010.
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] Telcordia GR-31-CORE LSSGR, Issue 4: "CLASS Feature: Calling Number Delivery", June
2006.
[i.2] Telcordia GR-1188: "LSSGR CLASS Feature: Calling Name Delivery, Generic Requirements",
April 2009.
[i.3] ANSI 0600407: "Network-to-Customer Installation Interfaces - Direct Inward Dialing Analog
Voicegrade Switched Access Using Loop Reverse-Battery Signaling", formerly T1.405.
[i.4] Telcordia GR-506: "LSSGR: Signaling for Analog Interfaces", December 2006.
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9 ETSI TS 103 161-15 V1.1.1 (2011-10)
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the terms and definitions following apply:
endpoint: terminal, gateway or Multipoint Conference Unit (MCU)
gateway: devices bridging between the IPCablecom IP Voice Communication world and the PSTN
NOTE: Examples are the Media Gateway, which provides the bearer circuit interfaces to the PSTN and
transcodes the media stream, and the Signalling Gateway, which sends and receives circuit switched
network signalling to the edge of the IPCablecom network.
trunk: analogue or digital connection from a circuit switch that carries user media content and may carry voice
signalling (M , R , etc.)
F 2
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
CAS Channel Associated Signalling
CMS Call Management Server
DID Direct Inward Dialling
DOD Direct Outward Dialling
DTMF Dual-tone Multi Frequency (tones)
E&M E and M Signalling
GS Ground-start
LS Loop-start
MTA Multimedia Terminal Adapter
NCS Network-based Call Signalling
PBX Private Branch Exchange
PAT IPCablecom Analog Trunking (package)
PSTN Public Switched Telephone Network
RLCF Reverse Loop Current Feed
4 Void
5 Overview
The present document describes the functional requirements for an embedded client to support one-way incoming, one-
way outgoing, and two-way PBX trunks. The physical interfaces used to support these trunk types are also defined.
5.1 Functional Responsibility
To maintain compliance with the IPCablecom NCS specification [2], the Call Agent will remain responsible for all
higher order functionality whenever possible. Only when timing is critical will the endpoint be responsible for the
required functionality. For example, the endpoint is expected to out-pulse a string of successive digits when requested
by the Call Agent. In this case, the endpoint is responsible for the timing of the duration of each digit and the delay
between them.
The endpoint is also responsible for all timing requirements related to the start method in use - wink, delay or
immediate. In fact, the start method used by the interface is transparent to the Call Agent.
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10 ETSI TS 103 161-15 V1.1.1 (2011-10)
5.2 Physical Endpoint Interface
Various physical interfaces provided by an endpoint of an MTA are used to support the following PBX trunks:
• One-way incoming trunk - supports calls originating from the network towards the PBX via the MTA. A
specific example of a one-way incoming trunk is a DID PBX (direct inward dialling private branch exchange)
trunk which is to be provided using a DID PBX physical interface.
• One-way outgoing trunk - supports calls originating on the PBX towards the network via the MTA. A specific
example of a one-way outgoing trunk is a DOD PBX trunk which may be provided over a number of physical
interfaces.
• Two-way trunk - supports calls originating and terminating on the PBX via the MTA. A four-wire E&M
physical interface is typically used to support two-way PBX trunks; however, other interfaces may also be
used.
The following clauses describe each physical interface that may be provided on an MTA to support one or more of the
above defined PBX trunks.
5.2.1 Loop-Start Line Interface
The NCS Line package defined in the IPCablecom NCS specification [2] is used to support loop-start lines. Loop-start
lines are typically used for residential voice services, but may be used to support analogue trunking for PBX.
5.2.2 Ground-Start Line Interface
Ground-start signalling interfaces are used to provide two-way service to customer-installation switching systems, e.g.
legacy PBX systems.
According to [1] ground-start signalling for two-way dial facilities was introduced to reduce the likelihood of seizure of
the line at both ends during the silent interval of the alerting signal. Ground-start signalling is typically used on one-way
or two-way seizure PBX lines with Direct Outward Dialling (DOD) and attendant-handled incoming call service.
Ground-start lines are also used for automatically originated data service. The two-wire ground-start line conductors
transmit common-battery loop supervision, loop dial pulses or DTMF address signals, alerting signals, and voice-band
signals. Ground-start lines are often used rather than loop-start lines for the following reasons:
• To avoid simultaneous seizure, i.e. glare conditions.
• To allow the application of a dc voltage between tip and ring and the closure of a path from the tip conductor
to ground as a start dial signal.
• To provide a positive indication of network disconnect.
See [1] for the network interface requirements for ground-start access lines.
5.2.3 DID PBX Trunk Interface
A one-way Direct Inward Dialling (DID) trunk interface as described in [3] is required to support a DID interface of a
PBX. DID trunks can only make calls in the direction from the network towards the PBX.
Electrically, a DID trunk looks similar to the reverse of a 2-wire loop-start interface. The PBX provides loop current by
applying -48 volt battery to the ring lead and grounding the tip lead. The MTA signals off-hook and on-hook towards
the PBX by closing and opening the loop. The PBX signals answer supervision (off-hook) by reversing battery and
ground on the tip and ring leads [i.3]. The PBX signals call release (on-hook) by restoring battery to ring and ground to
tip. Since this is a one-way trunk, there is no ringing voltage as seen on a loop-start interface.
The MTA may dial using either dial-pulse at 10 pulses per second with 300 ms between digits or DTMF at 10 tones per
second. Dial-pulse may be done either by opening and closing the loop in a manner similar to loop-start dialling; or it
may use battery and ground pulsing. With dial-pulse interfaces, the network typically only dials the last 2 or 3 address
digits to minimize call setup delay.
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11 ETSI TS 103 161-15 V1.1.1 (2011-10)
The interface has three methods for start of dialling:
• Immediate start - The MTA starts dial-pulsing shortly after closing the loop indicating off-hook condition.
This method cannot be used for DTMF.
• Wink start - The MTA waits for the PBX to signal that it is ready to accept digits. The signal from the PBX is
a 200 ms battery reversal (off-hook).
• Delay start - The MTA waits for the PBX to signal that it is ready to accept digits. The signal from the PBX is
a battery reversal of at least 100 ms (off-hook) followed by restoration of battery (on-hook) some time later.
Of the three start-of-dialling methods, wink start is most common.
5.2.4 E&M
E&M is described in annex F of [3] and is typically used as a PBX tie trunk. E&M trunks may be configured to be 2-
way or 1-way. Signalling may be either dial pulse or DTMF. The interface is extremely simple and only off-hook and
on-hook are signalled in each direction. The PBX signals off-hook and on-hook on the M-lead (Mouth) and listens for
off-hook and on-hook signals on the E-lead (Ear). The three dialling methods found in DID are also used in E&M.
The interface has three methods for start of dialling:
• Immediate start - The calling side of the interface goes off-hook. It starts dial pulsing shortly afterwards (at
least 65 ms). This method cannot be used for DTMF.
• Wink start - The calling side goes off-hook and waits for the called side to signal that it is ready to accept
digits. The signal from the called side is a 200 ms off-hook wink.
• Delay start - The calling side goes off-hook and waits for the called side to signal that it is ready to accept
digits. The signal from the called side is an off-hook transition within 150 ms of detecting off-hook and lasting
at least 140 ms followed by an on-hook some time later.
Answer supervision is transmitted on the called side by a transition to off-hook.
Release supervision is transmitted by a transition to on-hook.
5.2.4.1 Two-wire E&M
Two-wire E&M (or Type I E&M) has two conductors on the interface called the E-lead (or Ear) and the M-lead (or
Mouth). The PBX provides -48 volt battery on both leads. The MTA signals off-hook by shorting the PBX E-lead to
ground. The PBX signals off-hook by closing a contact to provide battery to the M-lead.
5.2.4.2 Four-wire E&M
Four-wire E&M (Type II E&M) has four conductors called the E-Lead, the M-Lead, Sleeve Battery, and Sleeve
Ground. The PBX applies -48 volt battery to the E-Lead and grounds the Sleeve Ground. The MTA provides -48 volt
battery on the Sleeve Battery and grounds the M-Lead with a current detector. The MTA signals off-hook by shorting
the E-Lead to Sleeve Ground. The PBX signals off-hook by shorting the M-Lead to Sleeve Battery.
5.3 NCS Package Support
In order to avoid the unnecessary complexity of supporting redundant signals and events, an additional package above
and beyond the NCS Line package is defined here to include only those events and signals that are needed to support
analogue trunking for PBX, but do not already exist in the NCS Line package. Due to this design, the PAT package
relies heavily on the NCS Line package. In other words, both packages must be supported when providing analogue
trunking for PBX.
As shown in table 1 below, support for the NCS Line package is required regardless of the interface type and service
provided. Support for the PAT package is required only for analogue trunking for PBX.
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12 ETSI TS 103 161-15 V1.1.1 (2011-10)
6 Analog Trunking for PBX Functional Requirements
In general, support for analogue trunking for PBX as defined in the present document is optional, i.e. not required for
IPCablecom compliancy. Analog Trunking for PBX is an add-on to existing functionality already defined in other
IPCablecom specifications.
Table 1 describes the support required based on the physical interface type. In some cases the configuration parameter
does not apply to the particular interface or trunk type. In this case, the parameter is marked as "Not Needed".
Table 1: Interface Requirements Matrix
Interface Trunk Type NCS Package Start of Out-pulse Max Length
Type Support Dialling Dialling of Out-pulse
Method Method Dial String
Line PAT
Loop-Start Residential voice Yes No Dial tone Not Needed Not Needed
1-way incoming Yes Yes Not Needed Needed Needed
1-way outgoing Yes Yes Dial tone Not Needed Not Needed
2-way Yes Yes Dial tone Needed Needed
Ground-Start 1-way incoming Yes Yes Not Needed Needed Needed
1-way outgoing Yes Yes Dial tone Not Needed Not Needed
2-way Yes Yes Dial tone Needed Needed
DID PBX 1-way incoming Yes Yes Needed Needed Needed
E&M 1-way incoming Yes Yes Needed Needed Needed
1-way outgoing Yes Yes Needed Not Needed Not Needed
2-way Yes Yes Needed Needed Needed
T1 1-way incoming Yes Yes Needed Needed Needed
1-way outgoing Yes Yes Needed Not Needed Not Needed
2-way Yes Yes Needed Needed Needed
NOTE: For T1 the start method depends on the physical interface being emulated.

6.1 Endpoint Configuration
To support the trunk types defined in clause 5.2, the endpoint must be configured with the following:
• Physical interface type
• PBX Trunk type
• Start of dialling method
• Out-pulse dialling method
• Maximum length of out-pulsed dial string
• Re-seizure delay
6.1.1 Physical Interface Type Configuration
At any given point in time, an endpoint supports one and only one type of interface:
• Loop-start line interface
• Ground-start line interface
• E&M 2-wire line interface
• E&M 4-wire line interface
• DID PBX trunk interface
• T1
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13 ETSI TS 103 161-15 V1.1.1 (2011-10)
The question of how a particular endpoint is configured for a particular interface type is beyond the scope of the present
document. For example, the endpoint may be configured via provisioning or separate MTA hardware used to provide
the interface requirements defined here. The only point is that an endpoint - once configured - will provide one type of
interface.
See clause 5.2 for the interface requirements between the MTA and the PBX.
6.1.2 PBX Trunk Type Configuration
As stated in clause 5.2, the following PBX trunk types are supported:
• One-way incoming trunk
• One-way outgoing trunk
• Two-way trunk
The endpoint must be configured as such when used to interface to a PBX to provide one of the above trunk types.
When this configuration information is missing, the default behaviour is to provide residential voice service, which may
or may not be applicable to the physical interface (see table 1).
6.1.3 Start of Dialling Method Configuration
In order for the MTA to provide an interface to a PBX using either a PBX DID or E&M physical interface, the start of
dialling method must be configured to something other than the default "dial tone" method. The configured start of
dialling method for two-way E&M PBX trunks is used in both directions - PBX to endpoint and endpoint to PBX. For
loop-start and ground-start lines the default "dial tone" method must be used which indicates that dial tone is provided
as a signal to the PBX to start dialling. The start of dialling methods in which the endpoint may be configured are as
follows:
• Dial tone (default)
• Immediate start
• Wink start
• Delay start
6.1.4 Out-pulse Dialling Method
When an endpoint is configured to support incoming PBX calls, the endpoint will be expected to out-pulse a dial string
towards the PBX. In this case, the endpoint must be configured to out-pulse one of the following digit types:
• DTMF
• Dial Pulse
6.1.5 Maximum Out-pulsed Dial String Length
The Call Agent may provide the entire external phone number of the extension being dialled in the PBX. Typically,
however, only the last few digits are needed. As such, the endpoint must be configured with the maximum dial string
length when configured to support incoming PBX calls. When the Call Agent provides a dial string that exceeds the
maximum length configured, the endpoint must out-pulse only the last digits received up to the configured maximum
length. For example, let us say that the maximum out-pulsed dial string length is configured to be four and the Call
Agent provides the following dial string to out-pulse:
(1, 7, 7, 0, 5, 5, 5, 1, 2, 1, 2)
The endpoint would out-pulse only the last four digits in this case (1, 2, 1, 2).
The maximum out-pulsed dial string length is limited to 32 digits.
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14 ETSI TS 103 161-15 V1.1.1 (2011-10)
6.1.6 Re-seizure Delay
Due to PBX requirements once a trunk is released it cannot be seized again for a short period of time. The MTA must
be configured with the amount of time required to wait (in ms). The default is zero, i.e. no delay. The MTA must not re-
seize a trunk during this period of time. If a new Call Setup request is received during this time, the MTA must delay
execution of the command until such time has passed. The command must not, however, be rejected due to this
requirement.
6.2 Signalling Support
In order to help quickly detect configuration issues (e.g. endpoint is configured for residential voice while the Call
Agent is configured for PBX service), commands issued to the endpoint that are specific to a particular service must be
rejected when the endpoint is configured to support any other service. The reverse is also true. If the endpoint notifies
an event that is specific to a service other than its current configuration via the Call Agent, then the Call Agent must
reject the NTFY.
When an endpoint is configured for residential voice, independent of the physical interface, support for the PAT
package must be suppressed. As such, the endpoint must not include the PAT package in the list of supported packages
when audited via the AUEP command. An endpoint that is requested to detect an event or apply a signal that is specific
to the PAT package must return an error (error code 518 - unsupported or unknown package).
When an endpoint is configured to be a one-way or two-way PBX trunk, independent of the physical interface, the PAT
package must be fully supported. When endpoint capabilities are audited via the AUEP command, the PAT package
must be included in the list of supported packages. The default NCS Line package must also be included. If however,
the endpoint is requested to detect an event or apply a signal included in the NCS Line package according to table 2 that
the interface is unable to support an error must be returned (error code 512 or 513 - not equipped to detect event or
generate signal). Some signals/events that are shown to be "not required" are allowed to be requested by the Call Agent.
The endpoint must apply the signal or process the event as requested if the endpoint is physically capable of doing so.
NOTE: The T1 physical interface is not listed in table 2. The required signalling support for T1 mirrors the
physical interface being emulated.
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15 ETSI TS 103 161-15 V1.1.1 (2011-10)
Table 2: NCS Line Package Support
NCS Line Package Signal / Required for…
Event LS Residential LS/GS PBX E&M PBX Trunk DID PBX Trunk
Voice Trunk
0-9,*,#,A,B,C,D Yes Yes Yes No
bz Yes Yes Yes Yes
cf Yes No No No
ci(ti, nu, na) Yes No No No
dl Yes Yes Yes No
ft Yes Yes Yes Yes
hd Yes Yes Yes Yes
hf Yes Yes Yes Yes
hu Yes Yes Yes Yes
L Yes Yes Yes No
ld Yes Yes Yes Yes
ma Yes Yes Yes Yes
mt Yes Yes Yes Yes
mwi Yes No No No
oc Yes Yes Yes Yes
of Yes Yes Yes Yes
osi Yes No No No
ot Yes No No No
r0, r1, r2, r3, r4, r5, r6 or r7 Yes No No No
rg Yes No No No
ro Yes Yes Yes Yes
rs Yes No No No
rt Yes Yes Yes Yes
sl Yes No No No
t Yes Yes Yes No
TDD Yes Yes Yes Yes
vmwi Yes No No No
wt1, wt2, wt3, wt4 Yes No No No
X Yes Yes Yes No
There are some special considerations related to the use of the NCS Line package with analogue trunking for PBX as
detailed in the clauses below.
6.2.1 Digit and Digit Related Events
When the endpoint is expected to receive digits from the PBX and the Call Agent is to be notified of these events, the
Call Agent must use the NCS Line package digit (0-9,*,#,A,B,C,D,X) and digit related events (L, t) to request them.
The Call Agent may request the processing of digit events in any manor allowed by NCS. For example, the endpoint
may be instructed to collect digits according to a supplied Digit Map.
6.2.2 Digit Events over E&M
When an E&M PBX trunk is setup to use a start of dialling method of "immediate start" the Call Agent should take
special precautions to insure that digits are not missed from the PBX. The PBX will start dialling after a short delay
after going off-hook. This may occur before the Call Agent requests digits from the endpoint after being notified of the
off-hook event. There are mechanisms allowed by NCS to guard against this. For example, the endpoint may be
instructed to quarantine digits while in this state. This is accomplished by the use of the detectEvents parameter.
Another option is to use an embedded request to instruct the endpoint to autonomously collect digits upon off-hook
detection. See [2] for more information.
6.2.3 Local Tones
Though only a few local tones (MTA ≥ PBX) are required for analogue trunking for PBX as indicated in table 2, each
physical interface should be capable of applying all requested NCS Line package tones towards the PBX. To maintain
as much flexibility as possible and to support potential future PBX-like features, the endpoint must apply the requested
tones (with noted exceptions below) as per the rules of NCS as long as the endpoint is physically capable of doing so.
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16 ETSI TS 103 161-15 V1.1.1 (2011-10)
6.2.3.1 Local Tones over E&M
Dial tone is not applied over an E&M physical interface. When either dial-tone (L/dl), stutter dial tone (L/sl) or message
waiting indicator tone (L/mwi) is requested by the Call Agent to be applied over an E&M interface, the MTA must not
apply the tone itself. Instead, the MTA must use the signal request to aid in detecting "no dial" occurrences. As such,
the MTA must generate an operation complete event if digits are not detected in time just as it does when dial tone itself
is applied (as long as the "keep alive" action is not used in the request).
NOTE: This is simply one example of a timeout signal being stopped by the occurrence of an event. All NCS
rules governing the application of a timeout signal is to be followed.
All other local tones, when requested, are applied towards the PBX over an E&M interface.
6.2.4 Caller ID and VMWI
The Caller ID and VMWI NCS Line package signals apply only to LS/GS (loop-start/ground-start) PBX trunk
interfaces.
The call setup (PAT/sup) signal defined in the PAT package is used to deliver caller ID information; however, the Call
Agent may alternatively use the Line package Caller ID signal to provide caller ID information. Though the PBX
typically only expects to receive caller ID information during call setup, the Call Agent may use the Line package
Caller ID signal to attempt to display caller ID when the PBX is off-hook (e.g. Caller ID with Call Waiting). To
maintain as much flexibility as possible with the use of the NCS Line package the endpoint must honour such a request
and attempt to deliver the caller ID information as defined in NCS.
The same is true of VMWI. Though the PBX typically does not expect to receive VMWI information, the Call Agent
may use the Line package VMWI signal. To maintain as much flexibility as possible with the use of the NCS Line
package the endpoint must honour such a request and attempt to deliver the VMWI information as defined in NCS.
6.2.5 Hook Events
For all physical interface types, the NCS Line package hook events (L/hd, L/hf, L/hu) are used to indicate hook state at
the PBX.
For LS/GS, hook events are detected and generated as defined in NCS.
Similarly, for E&M, on-hook and off-hook events are generated when the corresponding signal is detected from the
PBX. Based on timing, a flash-hook event may also be generated.
For DID battery reversal is considered to be an off-hook signal from the PBX. Likewise, the transition from reversed to
normal battery is considered an on-hook signal. Battery removal is also considered to be an off-hook signal from the
PBX. The transition from no battery to battery being detected is considered to be an on-hook signal. Based on the
timing of the battery events, e.g. battery removal followed by battery restoration, a flash-hook event may also be
signalled by the PBX. The endpoint must generate the corresponding NCS Line package hook events.
NOTE: A PBX uses an off-hook signal to block further calls from being initiated on the trunk.
For T1, in addition to the emulated on-hook and off-hook events, a red alarm condition indicates that no further calls
may be processed; however, an off-hook event must not be generated when this condition occurs. Instead the endpoint
must be taken out of service and an RSIP Forced must be sent to the Call Agent.
6.2.6 Open Signal Interval
For loop-start lines the L/osi NCS Line package signal is used as a trigger for the endpoint to perform a "timed
disconnect release". For ground-start lines, the signal is used as a trigger for the endpoint to provide a "guard release"
which has similar characteristics to the loop-start "timed disconnect release". This signal is defined in [i.4] in general
terms as an "open signal interval" for both loop-start and ground-start interfaces.
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17 ETSI TS 103 161-15 V1.1.1 (2011-10)
For all PBX trunks, the PAT/rel signal is used as a trigger for the PBX to release the call. For LS/GS the semantics are
identical to the L/osi signal. In order to maintain the concept of a physical layer abstraction to the Call Agent and to
provide the increased flexibility of the L/osi signal for LS/GS, the L/osi signal is further defined to be identical to the
PAT/rel signal for E&M and DID physical interfaces which results in an on-hook from the endpoint. As such, the L/osi
signal may be used by the CMS (call management server) as an alternative for PAT/rel for all physical interface types.
For GS/LS the Call Agent may adjust the OSI interval using the L/osi signal parameterized with the "to" parameter, e.g.
L/osi(to=800). For E&M and DID, however, the "to" parameter has no effect and, if provided, must be ignored.
6.2.7 Ring Requests
The ring NCS Line package signal requests only apply to LS/GS trunks.
The call setup (PAT/sup) signal defined in the PAT package is used as a trigger to seize the trunk by applying standard
ringing; however, the Call Agent may alternatively use the Line package RG signal to provide ringing. Though the PBX
typically only expects to receive standard ringing, the Call Agent may request other defined the Line package ring
signals (R0 - R7, RS) to seize the trunk. To maintain as much flexibility as possible with the use of the NCS Line
package the endpoint must honour such a request and attempt to seize the trunk using the defined ring signal.
6.2.8 T1 Trunk Signalling Requirements
T1 is a digital trunk interface. As such, the signalling between the MTA and PBX required to support one-way
incoming, one-way outgoing and two-way PBX trunks is emulated using Channel Associated Signalling (CAS). The
signalling between the MTA and Call Agent, however, remains unchanged. In other words, the fact that the physical
interface is emulated digitally is of no consequence to the Call Agent.
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18 ETSI TS 103 161-15 V1.1.1 (2011-10)
Annex A (normative):
Event Packages
This clause defines a set of event packages for the various types of endpoints currently defined by IPCablecom for
embedded clients.
Each package defines a package name for the package and event codes and definitions for each of the events in the
package. In the tables of events/signals for each package, there are five columns:
Code The package unique event code used for the event/signal.
Description A short description of the event/signal.
Event A check mark appears in this column if the event can be Requested by the Call Agent. Alternatively,
one or more of the following symbols may appear:
"P" indicating that the event is persistent,
"S" indicating that the event is an event-state that may be audited,
"C" indicating that the event/signal may be detected/ap
...