MGCP fallback

[fran19422]

Hello, during MGCP fallback when the WAN link fails to CUCM, I understand H323 is reverted to.

So that I can understand better:

- "....When the WAN link fails, the fallback feature keeps the gateway working as an H.323 or SIP gateway":

. Does this mean that H.323 or SIP is used for internal call routing ? because it could not be used for any outbound calls due to the IP WAN having gone down - Am I correct here ?

- now that there is no IP WAN link does this mean any outbound calls will have to use an ISDN or POTS connection to get calls out to the PSTN ?

[Jorge Armijo · Accepted solution]

Yes, when the WAN link goes down, you can use MGCP fallback and use default application for call routing:

http://www.cisco.com/en/US/tech/tk1077/technologies_tech_note09186a0080144630.shtml

http://www.cisco.com/en/US/tech/tk1077/technologies_configuration_example09186a008012ecc6.shtml

When MGCP fails, the router uses the default application for call routing, as you would see it with the "debug voice ccapi inout".

Exactly, since there will not be WAN back to HQ, you can use POTS lines along with SRST to provide full fallback functions. You could also have a PRI, BRI or even SIP Trunk to route calls, however, POTS lines are the most commonly used for SRST.

HTH

--
Jorge Armijo

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