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R2 signaling is a channel associated signaling (CAS) system developed in the 1960s that is still in use today in Europe, Latin America, Australia, and Asia. R2 signaling exists in several country versions or variants, in an international version called Consultative Committee for International Telegraph and Telephone (CCITT-R2). The R2 signaling specifications are contained in ITU-T Recommendations Q.400 through Q.490.
E1 R2 signaling is an international signaling standard that is common to channelized E1 networks. E1 R2 signaling has been supported on the Cisco AS5200, 5300, and 5800 series access routers. E1 R2 signaling was introduced to the Cisco 2600/3600 series routers in Cisco IOS® Software Release 12.1.2XH and 12.1(3)T. E1 R2 is also supported on the E1 voice WAN interface cards (VWICs), which can be inserted into the WIC slot on the IAD2430s. Furthermore, Cisco AS5350, 5400, and 5850 also support this application.
Note: R2 signaling is not supported on the Cisco MC3810 router.
The purpose of this document is to offer some example configurations and important guidelines that will help customers set up an R2 interconnection. Troubleshooting is not covered as part of this document. For information on troubleshooting E1 R2, refer to E1 R2 Signaling Configuration and Troubleshooting.
There are no specific requirements for this document.
This document is not restricted to specific hardware versions; however, some software recommendations are made. These recommendations are based on the fact that major software defects that are related to this technology have been identified and addressed by the respective versions. Nonetheless, extensive testing is required before you use the software in a production environment.
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
Refer to Cisco Technical Tips Conventions for more information on document conventions.
This section provides a list of functional configuration examples that have been tested. These examples should be used as a reference when you provision E1 R2 in countries where the default settings do not apply.
Note: Only the commands under cas-custom are shown. The configuration of voice ports and dial peers is not covered. Cisco IOS Software Release 12.3(9) was used to test these configurations.
controller E1 0/0 framing NO-CRC4 ds0-group 1 timeslots 1-15,17-30 type r2-digital r2-compelled ani cas-custom 1 country telmex category 2 answer-signal group-b 1
Note: In some implementations, Telmex requires that Group A signals be used for automatic number identification (ANI) collection. If this is needed, add the command groupa-callerid-end under cas-custom. If this command is not configured, the router uses the country default (a Group C signal).
controller E1 0/0 ds0-group 0 timeslots 1-15,17-31 type r2-digital r2-compelled ani framing NO-CRC4 cas-custom 0 country argentina dnis-complete
Note: For most configurations, Telecom Argentina requires that an I-15 signal be sent after the last DNIS digit is dialed. If this is the case, configure dnis-complete. By default, an I-12 signal is used.
For incoming calls:
controller E1 0/0 framing NO-CRC4 ds0-group 0 timeslots 1-15,17-31 type r2-digital r2-compelled ani cas-custom 0 country venezuela answer-signal group-a 6 dnis-complete
Note: CANTV Venezuela uses A6 for answer signal.
For outgoing calls:
controller E1 0/2/0 framing NO-CRC4 ds0-group 1 timeslots 1-15 type r2-digital dtmf dnis
controller E1 0/0 framing NO-CRC4 ds0-group 0 timeslots 1-15,17-31 type r2-digital r2-compelled ani cas-custom 0 country brazil category 2 answer-signal group-b 1
Note: Some Telefonica circuits require metering to be enabled. If needed, add the metering command under cas-custom.
controller E1 0/0 framing NO-CRC4 ds0-group 0 timeslots 1-15,17-31 type r2-digital r2-compelled ani cas-custom 0 country china answer-signal group-b 1
The following is a list of software caveats related to E1 R2. In order to follow these bug ID links and see detailed bug information, you must be a registered user and you must be logged in.
|Cisco Bug ID||Description|
|CSCed55231||MRP does not clear R2 call cleanly|
|CSCed22834||ICS7700 does not recognize inbound BLOCKING state|
|CSCec77853||One way audio with SIP and E1 R2|
|CSCec64185||E1 R2: Bad implementation of A-2 signal for Argentina|
|CSCec58903||E1 R2: AS does not detect BLOCKING state|
|CSCea55028||voice call stuck if call setup time takes more than 15s|
|CSCea17341||Calls fail with answer signal group A and no DID configured|
|CSCdz69604||5400 E1 R2 is not sending answer signal group A|
|CSCeb36413||E1 R2 call fails on 5400 and 5850|
|CSCdy36274||E1 R2 hung call when redial to same destination|
|CSCea64554||Call stuck on 3600 when hairpining from E1 R2 to ISDN|
|CSCea61403||Unprotected buginf in R2 calls|
|CSCed44156||E1 R2 needs configurable DNIS timeout for 2600|
|CSCdy22974||Spurious memory access at tsp_voice_call_check on OGW|
|CSCdx66463||R2 voice port locks up in R2_Q421_IC_CLR_BWD state|
|CSCea81777||Hairpin call get disconnect from E1 R2 to CAS E&M|
|CSCeb52314||AS5850 chooses a DS0-group not defined on the POTS dial-peer|
|CSCdz66927||Voice-ports Hung and Digits not being pulsed out|
|CSCeb65150||E1 R2 Needs configurable DNIS timeout for 7200 series|
Cisco has recently added new commands for E1 R2 implementations, to improve the flexibility of this application and to meet customer demands. These are the most important commands:
alert-wait-time—Time to wait for alert indication for incoming R2 calls. Default is 15 seconds.
call guard-timer—To set a guard timer to accept or reject a call, in the event that the RADIUS server fails to respond to a pre-authentication request.
cause-on-congestion—Translates the R2 congestion signal to the ISDN cause value, in order to return this value to the originating voice gateway.
disconnect-tone—Provides a tone to the calling party after the ending Group B register signal.
signal-end-to-end—Transfer R2 Category and Answer signals end-to-end.
trunk-group label —Configure interface to be in a trunk group.
Note: Some of those commands are platform-specific. Refer to the Command Lookup Tool for details about every option.