For most voice protocols, the interface chosen is the 'closest interface'. Generally, you can a 'show ip route x.x.x.x' and see which interface it will use to access.
A lot of routing protocols will use the highest loopback value as the Router ID / source. Offhand, I can't think of a voice situation that uses this; not to say it's not possible. If you're sending/receiving routing protocol information on that interface it's very likely the router will choose that interface.
If you have a router with more than one interface, you should have a bind command.
Loopbacks are handy for using IP addresses that are used for management and are easier to remember. They're used more often used for devices with multiple IP addresses so that they can be managed and reached with a single address. If your device (like a CMM) only has a single IP address, it will offer much less service.
What was found by the onsite folks was when I put in the loopback and activated. Apparently all incoming calls were registering with the loopback address (or trying) instead of the interface. I assume this is related to your statement of highest/lowest vlan/loopback interface. Ok, this said apparently a bind statement was needed to ensure the bind to the correct interface. I just can't find documentation on this aspect.
I'm not able to access my old voice mail messages all of a sudden. The recording says something like 'the message is currently not available'. This has never happened before in all the years I have been using this system. I have t...
If you have 2 ISR routers, one acting as Failover, do we need to have both the same number of SRST licenses on the 2 routers?
No. You will only need the SRST licenses on the primary router. Because this feature...