cucm wont send or receive voice through working sip trunk

[baselzind]

i have a cucm 11.5 which is connected through two sip trunks to two cucm of the same version through site to site vpn, the sip trunk is up and i can call them and receive calls , recently when i call them i cant hear them and they cant hear me , but when they call ,me the call is fine? the exact same problem is happening with the two sites im connected through sip trunk

[Dennis Mink]

This is most likely a routing issue. If your cube is flow through. Your cube will need to be able to route to all phones and vice versa. Also if you have a fw in the path allow rtp from cube to all voice subnets

[baselzind]

no there is no cube in use , i have a direct sip trunk with the other cucm , the calls get answered but there is no voice , plus the sip trunk from my side keep going up and down