[cisco-voip] CME-SRST to CUCM 6.1 xfer issues

[Tim Smith]

Hi Guys,

Just thought I would throw this out there, if any one has any advice, much
appreciated. I'll probably go with a tac case shortly :)

I have 2 x CME-SRST routers at Site 1 - each router terminates an ISDN PRI
circuit.
Phone 1 - registered to CME-SRST Router 1 at Site 1
Phone 2 - registered to CUCM v6.1(5) at Site 2
WAN Router 1 at Site 1 connects to WAN Router 2 at Site 2 via Ethernet link.
WAN Router 2 is configured as a H323 gateway in CUCM
WAN Router 1 and 2 are configured as IP to IP voice gateways

Dial peer is configured from both CME-SRST routers which points to WAN
Router 1
WAN Router 1 then has dial peer that points to WAN Router 2
WAN Router 2 has a dial peer that points to CUCM
This part of the call flow works correctly, I can dial Phone 2 directly
through both ISDN PRI's

Exact problem I have is as follows;
Inbound call on PRI connected to CME-SRST Router 2 to Phone 1
Routed via H323 dial peer to CME-SRST Router 1 and connected to Phone 1
succesfully
Phone 1 attempts blind xfer to Phone 2
Phone 2 rings and the call seems connected
A few seconds of dead air
Then disconnection with ISDN disc conn cause of Resource Unavailable

If the call originates on Router 1 ISDN to Phone 1 - the transfer is fine.

CME Routers are 3845 12.4(15)T13
The two wan routers also running the same code. A 3640 and 2811.

I have allowed H323 to H323 connections on all routers
I have enabled EmptyCapabilitySet on all routers
I have enabled H450.12 supp services on all routers
I have enabled H323 slow start on all routers
I have disabled "Wait for far end H.245" on the H323 gateway in CUCM.
(Without this - Phone 2 rings and I answer it but the originating phone
continues to play ring back unaware Phone 2 has been picked up)
Also tried H225 connect pass through
WAN Router 2 should have a SW MTP and HW Transcoder resource available.
I did try to force MTP for this.
Codec is G.729

I know it seems like a complex setup, so I am also trying to think of ways
to simplify it.
The reason it goes through the 2 x WAN routers as IP to IP and not directly
to CUCM from either CME router - is to enforce a max - number of calls
across this link.
It is a backup only scenario.

I have some ideas I am working through, but would be very open to any
others!

One thing that crossed my mind, is would SIP be a better alternative for the
routing. Maybe it is better equipped to handle all the transfers / back to
backing.

Cheers,

Tim
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://puck.nether.net/pipermail/cisco-voip/attachments/20100718/48851812/attachment.html>