We have the following topology at one location: Cisco Call Manager <- - > 6608 PRIs <- -> PBX <- -> PSTN

At another facility we have the following topology:

Cisco Call Manager <- - > IOS MGCP G/W<- ->PSTN

Here is my problem - in scenario 1 above, the Cisco dial plan passes the 9 across the 6608s to the PBX and the PBX performs the digit strip.

In scenario 2 above, the CCM PSTN route patterns perform the 9 digit strip and send the call to the PSTN.

How can I create redundancy for phones at both location so that if their primary PSTN connection fails, they will seek the other PSTN connection - specifically, how can I handle the 9 being required in scenario 1 and being stripped in scenario 2?