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VG224 w/ CUCM & SRST


Anyone running a VG224 with CUCM as SCCP, and failing over to SRST via H323?

Is this configuration possible?  I've seen documentation on going from MGCP to H323, but I'm not aware if it is possible to go from SCCP to H323.


Re: VG224 w/ CUCM & SRST

VG224 is IOS based which can run either H323 or MGCP to communicate with CUCM. You can use SCCP only with VG248 which is not an IOS based device.

Following commands allow you to fallback during SRST (H.323). You need to configur both SRST router and VG224.

Gateway# call application alternate default

Gateway# ccm-manager fallback-mgcp

MGCP works great with VG224. Make sure you upgrade your VG to the latest IOS.


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Re: VG224 w/ CUCM & SRST

mightyking, you are incorrect...the vg224 does support sccp.

sccp is required for supplementary features


Re: VG224 w/ CUCM & SRST


Re: VG224 w/ CUCM & SRST

Have you go this to work ? I`ve configured this before and my SI confirmed that the only way it worked was using CME,SRST. If you fail over to SRST and enter Show ephone registered , you do not see the VG`s or if  you do then  you do not see the DN`s concerned. I had to configure the VG224 as SCCP and then use CME, SRST  feature with the MAC address and DN of the VG configured in the CME. The phones do not be added and will re-register to the router in the normal way with SRST. - Can you post the steps if you have cit configured and more importantly tested in SRST- thanks 

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Re: VG224 w/ CUCM & SRST

abluenow – If I understand your question I believe we maybe doing what you’re after.  We have a remote site running SRST.  We have on site the following:

WAN Router – Cisco 3825 ISR (with just two interfaces, one to WAN the other to our Catalyst 3560 PoE 48-Port Switch)

SRST Router – Cisco 2821 ISR which supports analog (DID and FXO) interfaces and acts as the fallback when the WAN link fails (one interface just to the Catalyst 3560 PoE 48-Port Switch).  Because of the analog interfaces, this voice gateway is setup for H323 (I’d personally rather have used MGCP but that protocol doesn’t support the analog interfaces).

Layer 3 Switch - Catalyst 3560 PoE 48-Port Switch tying everything together.

VG224 – Supporting analog phones, modems (yeah, we still use some of those), and fax machines. 

The VG224 is set up as an SCCP voice gateway.  In Communications Manager (version 6.1) the VG224 uses Protocol SCCP.  The configuration on the VG224 is:

stcapp ccm-group 1





voice service voip

fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback cisco

modem relay nse codec g711ulaw gw-controlled



ccm-manager sccp local FastEthernet0/0



sccp local FastEthernet0/0

sccp ccm identifier 1 priority 1 version 3.1

sccp ccm identifier 2 priority 2 version 3.1

sccp ccm identifier 3 priority 3 version 3.1

sccp ip precedence 3



sccp ccm group 1

bind interface FastEthernet0/0

associate ccm 1 priority 1

associate ccm 2 priority 2

associate ccm 3 priority 3

switchback method graceful

The third CCM listed is the local SRST router (our 2821 ISR).  This SRST router doesn’t have any “special” to support the VG224.  Of course we loaded the 2821 ISR up with DSPs, it supports the local conference bridge, MTP (for call park, etc.) and transcoding.  It also sources MoH for the location. 

We tested this both in our lab and during deployment.  Each time the Communications Manager servers were cutoff from the remote site (and during deployment we did that with ACLs on the 3825 WAN router) the VG224 (and all the IP phones) failed over (after about two minutes) to the on-site Cisco 2821 ISR.  As long as the translation patterns were good (and that took a while to get just right), we were able to route “on-net” calls out the local analog interfaces without any issues. 

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Re: VG224 w/ CUCM & SRST

Thanks for your response Ken.

My question is specific to when the VG224 fails to SRST, can the protocol between the SRST router and VG224 be H323.

The issue that I have is that my SRST router can not support all of the analog phones as sccp, there are a total of say 135 phones at the remote site and we only have a 2851 in this example.  This is why I would like to run H323 in the SRST scenerio.  I'm wondering if i can have two dial peers on the VG224 for each phone with different preferences, one as sccp and one as H323; this way SCCP to CUCM, H323 to SRST router.

If the above is not possible, with your current scenerio, do you know if you are able to assign different ports on the same VG224 to different device pools?  I'm wondering about the possibility of configuring specific phones on each VG that will and will not register to the local SRST router (in the SCCP scenerio)

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