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H.323/MGCP Call Preservation - When to use what?

I have a couple of questions. First, what is best practice on configuring H.323 gateway for call preservation? Assume a remote site with a PRI where the phones are registered back to CCM at HQ. I've seen 3 different configs and don't know when to use which:

voice service voip

h323

no h225 timeout keepalive

voice service voip

h323

call preserve

voice class h323 1

h225 timeout tcp establish 3

The second question is regarding MGCP fallback. I know that when an MGCP gateway fallsback to H.323 during SRST that active PRI calls will drop because of the D-channel backhaul. However, when there are active calls in SRST and the router goes back to MGCP, will those calls drop while it re-establishes MGCP or is there a way to have call preservation for those calls since they were set up via H.323 gateway?

2 REPLIES
Bronze

Re: H.323/MGCP Call Preservation - When to use what?

michael,

second choice is the supported official version of call preservation.

For MGCP call preservation is not supported at present.

http://www.cisco.com/en/US/products/sw/iosswrel/ps5207/products_configuration_guide_chapter09186a00802b45e0.html#wp1149764

regards

mehmet

Bronze

Re: H.323/MGCP Call Preservation - When to use what?

>voice class h323 1

> h225 timeout tcp establish 3

>!

This command is for new calls only; it will change the timeout from the default of 15 seconds when hunting through the dial-peers. Since the timeout for ISDN is 10 seconds, you need the timeout to be less than that in order for new calls to be established when target of the primary dial-peer is unavailable. 2-5 seconds is the recommended setting

>voice service voip

> h323

> no h225 timeout keepalive

>!

It's my understanding this is to preserve calls when going from a CallManager to an SRST gateway, but not from one CallManager to another.

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