H.323 Call Preservation - Or Lack There Of!

Anyone know if call preservation actually works on an MGCP gateway configured for SRST/MGCP Fallback when using a partial PRI (manually configured)? I lose the call in the lab as soon as MGCP fallback kicks in – basically as soon as the command “isdn bind-l3 ccm-manager” is automatically removed from the config and the PRI D channel is bounced.

Everything else works fine after the D channel is brought back up.

voice service voip
h323
no h225 timeout keepalive
call preserve

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shodown

pitviper wrote: »

Anyone know if call preservation actually works on an MGCP gateway configured for SRST/MGCP Fallback when using a partial PRI (manually configured)? I lose the call in the lab as soon as MGCP fallback kicks in – basically as soon as the command “isdn bind-l3 ccm-manager” is automatically removed from the config and the PRI D channel is bounced.

Everything else works fine after the D channel is brought back up.

voice service voip
h323
no h225 timeout keepalive
call preserve

I thought only T1 CAS calls were kept up during the fallback. I don't have a any books with me right now, but I thought that the PRI calls would have problems during the fail over if you were using MGCP. I may be wrong, but let me see

pitviper

OK, that makes me feel a little better.

I'll try it again but this time on the BR2 site which has an E1 CAS to the PSTN.

Also found this in the SRND:

There is no call preservation when MGCP fallback occurs for T1 and E1 PRI (only for MGCP analog and T1 CAS). Instead, all active calls are dropped when MGCP fallback occurs for PRI. With H.323 and SIP, you can achieve call preservation on T1 and E1 PRI with failover to SRST mode. Phones in SRST mode can dial out to the PSTN, and previously active calls are still preserved.

I guess it makes sense since the D channel clearly needs to bounce before the PRI becomes available in SRST mode - even for new outgoing calls.