we received a problem from a customer about their CUBE SIP , the customer can use the sip for out going call and it was working fine, but when people trying to call to their ip phone from outside, the phone will ring, when he pick up will no audio and got fast busy tone.
we try to change the early offer setting and mtp in CUCM , but same result.
we capture the ccsip message and found that , that CUBE keep sending invite message to CUCM, but the CUCM doesn't reply acknowledge message. any one know why would this happened ?
i attached the setting and debug in here and please help
CUCM -> sip trunk --> cube -->SIP --> ITSP
IP PHONE --> make call --> SIP success
outside call to ITSP -->SIP -->CUBE--> CUCM ip phone will ring but fail to pickup
finally we found out the root cause is the ASA block the RTP signal by SIP inspecting setting,
and the problem solved after enable it
thanks all !