Someone please help.

I've been racking my brain on this issue and need some help. Here is the situation. We have 2 dmvpn eigrp tunnels to a gateway router in a different country. We normally connect these tunnels through commercial sims cards via a cisco isr c1111 or a cradle point (can't remember the model number atm.) transport only the tunnels reside on a cisco 5915. The 1111 and the cradle point are only configured nat to dhcp then out the sim. No additional acls. Now we also host voip phones off these tunnels and we have 2 models the sccp 7945s and sip 8861s and they connect to a callmanager on the other end on the tunnel. Here is my issue: When the tunnel connects through the cradle point everything works fine. All traffic works and all phones register. When the tunnels connect via the 1111 all traffic works and the sccp 7945s will register but the sip 8861s do not. They get stuck on phone is registering. The 1111 only has configs in it to make the sim pull an ip and to nat a dhcp pool. I can not figured out for the life of me what could be causing this issue. Any suggestions would be greatly appreciated.