- Firmware version: Any
- Model: Linkus, Grandstream
The calls from Linkus to Grandstream Phone exist a bad voice quality issue. But calls between Linkus to Grandstream, Linkus are working fine. Also, calls from IP phone to IP phone are working.
Transcoding problem between iLBC to other codecs, all that seems the voice codes issue.
- Capture the SIP packet on PBX, and reproduce the issue.
- make a call between Linkus and SIP phone.
- make a call between SIP phones.
Download the packet, it shows the iLBC Frame Size is using 30ms, And the Linkus mode is 20ms
Access the Grandsteam SIP phone WEB, and change the iLBC Frame Size to 20ms. Or remove iLBC codec.