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S20: Codec/transcoding problem with call transfer / forwarding

Enn Vee

September 14, 2021 15:26

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Hi, we have a massive problem with call transfer / call forwarding with a Yeastar S20. The scenario:

1. Mobile1 calls Yeastar -> working
2. Yeastar calls Mobile2 on Line2 -> working
3. Transfer Mobile1 to Mobile2 -> One way audio, Mobile1 can't hear anything

The same thing happens when forwarding a client to a mobile number - when the call is recieved by Mobile2, the calling party can't hear anyhting.

We checked the PCAP trace as we thought of NAT problems, but all SIP and RTP packages look well and the Yeastar S20 gets all audio packages.

What we noticed: The two calls always use different codecs (eg. G.722 and G.711). When we only allow 1 codec in Yeastar trunk, everything works fine.

Yeastar LVL1 support told us this is a known bug. But how can this everyday scenario be a known unfixed bug?!

What kind of bug is this and how can we fix it (without only allowing 1 codec)?

Thanks for every help!

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2 comments

• 0
  
  Eric Jiang September 15, 2021 00:53

  Hi Enn Vee,

  We will provide temporary firmware to fix this issue soon.

  You mentioned there are massive problems may I know what else do yo meet except for this codec transition issue?

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  Enn Vee September 15, 2021 07:32

  Hi Eric Jiang,

  thank you for your fast reply. Not being able to transfer calls because of this transcoding thing is a "massive issue" to us, because absolute basic functionality is missing here. Besides, there are only a few minor issues e.g. with broken provisioning templates for SNOM D375 phones. However, we found workarounds for these.

  We are looking forward for the temporary firmware as we really need this functionality. Thank you!