Call transfer from a PSTN call to a federated user fails in Skype for Business Server 2019 and 2015

Symptoms

In Microsoft Skype for Business Server 2019 or 2015, User A sets Call Transferring to a federated user who is in a different Skype for Business online domain or Skype for Business Server environment. When User B, a PSTN caller, calls user A, and if user A transfers to a federated contact, the call does not transfer. Additionally, a “400 - Malformed Edge Proxy header” error message is logged in the Skype for Business client log.

Resolution

To fix this issue, install one of the folllowing updates:

• The July 2019 cumulative update 7.0.2046.123 for Skype for Business Server 2019, Front End server and Edge server.

• The March 2016 cumulative update 6.0.9319.235 for Skype for Business Server 2015, Front End server and Edge server.