Answered Question
Aug 17th, 2009

We have our VG224 configured as MGCP GW`s, we are looking to deploy SRST sites and have seen lots of configuration examples for SCCP SRST fallback with VG224 but no MGCP version of it- Does any one have any details with MGCP SRST fallback with VG`s- Is it done or should I use SCCP based. The VG`s are mostly for faxing thanks

Correct Answer by Nicholas Matthews about 7 years 6 months ago

If you would like the VG224 to re-register to a new device you would need to choose either SCCP/SIP/H323, but MGCP will not re-register to a SRST router.

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Nicholas Matthews Mon, 08/17/2009 - 07:42

The idea of SRST is that if the WAN connection is dropped, that you can still use your local PSTN ports for connectivity.

This doesn't apply to the VG224 because the only interface it has to the outside world is through Ethernet. The FXS ports will not normally provide any PSTN connectivity. You could technically hook it to an FXO port on a PBX or something similar, but this is a highly unlikely scenario.

SCCP fallback works because if CUCM goes down, the VG224 may still be able to register to a local SRST/CME router. A MGCP VG224 wouldn't register to a SRST/CME router, so it doesn't make much sense to have a SRST fallback VG224.



iptuser55 Tue, 08/18/2009 - 01:35


We will deloy the VG244 at a SRST which will register to the local SRST with local PSTN links. Are yuo saying tha if we want a site whci has SRST capability whicvh also has local VG224 the VG shoudl be configured as SCCP?. We are running fax`s from the vg244`s any problem with SCCP


Correct Answer
Nicholas Matthews Tue, 08/18/2009 - 05:55

If you would like the VG224 to re-register to a new device you would need to choose either SCCP/SIP/H323, but MGCP will not re-register to a SRST router.

iptuser55 Wed, 08/19/2009 - 04:37

I`ve now configured the VG224 as SCCP in CCM and with



All is working with the VG being registered with the SRST router in fall back mode . If I do a SHOW EPHONE REGISTER on the SRST I can see the ANG GW and if I do a SHOW SCCP ALL on the VG224 I can see the ports registered also to the SRST Router however if I call one of the ports based upon the DN I`ve configured in CCM I get busy. I`ve configured on the Voice-port in the VG224 CALLER-ID ENABLED - any ideas. Also if I do a SHOW EPHONE REGISTERED in the SRST router I can see the DN`s of my other IPT Phones- 794x, 76x but where on the same output would I see Analogue port DN`s

many thanks

iptuser55 Wed, 08/19/2009 - 06:19


I did the commend and saw the port registerd and idle when the VG was registered to CCM, fell back to SRST, VG registered to the SRST Router via SHOW EPHONE REGISTERED and I did a SHOW STCAPP DEVICE SUM on the VG and saw the ports were unregsitered and status was OOS

When I do a debug sccp all, I can the VG trying to register back to the CCM

Any Ideas`s?

Nicholas Matthews Wed, 08/19/2009 - 07:23

Hard to speculate - I would check the analog phone configuration for SRST. I know more about how this should work for CME registration than for SRST.


iptuser55 Wed, 08/19/2009 - 07:30


thanks- Can I configrre it as a H323 GW ? - do I just create Dial-Peers?

Nicholas Matthews Thu, 08/20/2009 - 05:26

Yes, the easiest way to understand the VG224 is to know it's just like a 2800, but it only has an FE port and 24 FXS ports. You can put SCCP, MGCP, H323, and SIP on it simultaneously.



This Discussion