Is the sbc local or remote?
It sounds like a port forwarding issue.
Mps uses 4 ports per channel, mgi is 2, i think the rtg is also 2.
There are upto 8 of each on the 7100.
Mps ports in your case 30128-30159, Rtg 30357-30372
These need to be fiwarded to the mp10a.

A wireshark trace will confirm if the sbc is honouring the port change on the invite packet from the os7100.