A better way to do this is to use static routes and loopback addresses.
On the first router create a loopback interface and use the h323 bind command to source the voip traffic from this interface -
interface loopback 0
ip address 10.1.1.1 255.255.255.0
h323-gateway voip bind srcaddr 10.1.1.1
assume we have 2 serial ports -
interface serial 1/0
ip address 20.1.1.1 255.255.255.0
!
interface serial 1/1
ip address 20.1.2.1 255.255.255.0
We then create 2 static routes with different metrics to point to the remote router's loopback interface (which has an IP address of 11.1.1.1) via the next hop address of the serial ports
ip route 11.1.1.1 255.255.255.255 20.1.1.2 50
ip route 11.1.1.1 255.255.255.255 20.1.2.2 100
The first static route will be prefered over the second because of the lower metric, so the traffic will go via serial 1/0. If the first link fails, the second floating static route will kick in and the traffic will be rerouted, so it gives an element of redundancy.
You then point your VOIP dial peers to the remote loopback IP address.
This approach gets around the need for route maps and potential issues with load balancing over equal cost paths.
The remote router has a similar config (loopbacks and static routes) that points back to the main site router.