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

Applicability

  • 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.

Analysis:

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

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Solution:

Access the Grandsteam SIP phone WEB, and change the iLBC Frame Size to 20ms. Or remove iLBC codec.

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2 Comments

  • 0
    Avatar

    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
    Avatar

    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.

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