Bad Voice Quality Happens when Calling from Linkus to Grandstream IP Phone


  • Firmware version: Any
  • Model: Linkus, Grandstream

Problem Description:

The calls from Linkus to Grandstream Phone exist a bad voice quality issue. The voice hears well if calls between Linkus. 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.
  1. make a call between Linkus and SIP phone.
  2. 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.



Have more questions? Submit a request


  • 0

    I had the same issue with Astra Phone today, Astra phone was enabled with all the codec, so I selected G711a(8K), G711a(16K) and G729, then its started working for me. Kindly update me the best settings to proceed with al other Astra SIP phones to be working with Linkus.

  • 0

    Hi All, we have the same issue with calls from GXP2170 IP Phones. Will the fix work for call from GXP to Linkus ? I do notice that on some occasions the GXP will select PCMCA ( First Codec in List ) and then we get the Robot sound. If we dial back again within a minute or two it connected with iLBC and sound is fine.


    Wait another 5 mins and call again and it hits PCMCA again.

  • 0

    I have similar problem between Yealink W80 IP Dect phones and Linkus

Please sign in to leave a comment.