Definition of Events for Channel-Oriented Telephony Signalling
RFC 5244
| Document | Type |
RFC - Proposed Standard
(June 2008; No errata)
Updates RFC 4733
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 5244 (Proposed Standard) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Cullen Jennings | ||
| Send notices to | (None) | ||
Network Working Group H. Schulzrinne
Request for Comments: 5244 Columbia U.
Updates: 4733 T. Taylor
Category: Standards Track Nortel
June 2008
Definition of Events for Channel-Oriented Telephony Signalling
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Abstract
This memo updates RFC 4733 to add event codes for telephony signals
used for channel-associated signalling when carried in the telephony
event RTP payload. It supersedes and adds to the original assignment
of event codes for this purpose in Section 3.14 of RFC 2833. As
documented in Appendix A of RFC 4733, some of the RFC 2833 events
have been deprecated because their specification was ambiguous,
erroneous, or redundant. In fact, the degree of change from Section
3.14 of RFC 2833 is such that implementations of the present document
will be fully backward compatible with RFC 2833 implementations only
in the case of full ABCD-bit signalling. This document expands and
improves the coverage of signalling systems compared to RFC 2833.
Schulzrinne & Taylor Standards Track [Page 1]
RFC 5244 Channel-Oriented Signalling Events June 2008
Table of Contents
1. Introduction ....................................................2
1.1. Overview ...................................................2
1.2. Terminology ................................................3
2. Event Definitions ...............................................4
2.1. Signalling System No. 5 ....................................6
2.1.1. Signalling System No. 5 Line Signals ................6
2.1.2. Signalling System No. 5 Register Signals ............7
2.2. Signalling System R1 and North American MF .................8
2.2.1. Signalling System R1 Line Signals ...................8
2.2.2. Signalling System R1 Register Signals ...............8
2.3. Signalling System R2 ......................................10
2.3.1. Signalling System R2 Line Signals ..................10
2.3.2. Signalling System R2 Register Signals ..............10
2.4. ABCD Transitional Signalling for Digital Trunks ...........12
2.5. Continuity Tones ..........................................14
2.6. Trunk Unavailable Event ...................................14
2.7. Metering Pulse Event ......................................15
3. Congestion Considerations ......................................15
4. Security Considerations ........................................16
5. IANA Considerations ............................................17
6. Acknowledgements ...............................................20
7. References .....................................................20
7.1. Normative References ......................................20
7.2. Informative References ....................................21
1. Introduction
1.1. Overview
This document extends the set of telephony events defined within the
framework of RFC 4733 [4] to include signalling events that can
appear on a circuit in the telephone network. Most of these events
correspond to signals within one of several channel-associated
signalling systems still in use in the PSTN.
Trunks (or circuits) in the PSTN are the media paths between
telephone switches. A succession of protocols have been developed
using tones and electrical conditions on individual trunks to set up
telephone calls using them. The events defined in this document
support an application where such PSTN signalling is carried between
two gateways without being signalled in the IP network: the "RTP
trunk" application.
In the "RTP trunk" application, RTP is used to replace a normal
circuit-switched trunk between two nodes. This is particularly of
interest in a telephone network that is still mostly
circuit-switched. In this case, each end of the RTP trunk encodes
Schulzrinne & Taylor Standards Track [Page 2]
RFC 5244 Channel-Oriented Signalling Events June 2008
audio channels into the appropriate encoding, such as G.723.1 [13] or
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