We are currently running a hybrid environment, migrating slowly from Genesys DX (formerly Bold360) to Genesys Cloud.
When an agent on the GC side needs to transfer a voice call back to a legacy DX queue, we send it over a dedicated SIP tie-trunk. We have configured the trunk to support REFER so the media drops off our Edge and routes directly between the carrier and the DX gateway. However, the REFER is being rejected by the DX side with a ‘400 Bad Request - Invalid Contact’, forcing the Edge to anchor the media and trombone the call. Has anyone successfully established a clean SIP REFER release between GC and DX?
I had to write the comms strategy for our rollout when we hit a similar snag! The issue usually stems from the Contact header format that Genesys Cloud sends in the REFER message.
By default, the Edge uses an opaque, auto-generated string for the contact URI. Legacy PBXs (and some older DX components) expect a strict E.164 number format in the URI user part. You might need to look at your outbound routing rules and see if you can normalize that header before it leaves the trunk.
I manage 15 BYOC trunks and deal with this constantly. The issue is likely the ‘Replaces’ parameter.
When Genesys Cloud issues a REFER, it often includes a Replaces header to ensure a seamless transfer (Attended Transfer). If the DX gateway doesn’t support the Replaces extension (RFC 3891), it will reject the REFER with a 400 error. Check your Trunk settings in GC under ‘Protocol’. There is a toggle called ‘Consult Transfer Type’. If you change it from ‘Attended’ to ‘Blind’, the Edge will issue a standard REFER without the Replaces header, which the DX gateway should accept, allowing the media to drop cleanly off the Edge.