My GrandStream UCM6510 is configured like this: Inbound => SIP Trunk (VoIP Trunk) => IVR => Queue.
Currently, it has the following issue:
- When incoming call is made, no sound or ring plays
- In the CDR, it shows that call is failed
- The call does not reach to IVR yet
- It happens many time in day, about 10% of total calls (total is around 1000 incoming calls/day)
- I have checked the trunk provider, no issue from them
Please help me to fix this issue.