Consider the following scenario:
- You deploy Enterprise Voice in a Microsoft Lync Server 2013 environment.
- You set the EncryptionLevel setting to SupportEncryption in the media configuration for Mediation server.
- You configure a simultaneous ring to a Public Switched Telephone Network (PSTN) number.
- You log on to a Lync (Skype for Business) client that supports encryption or to a Lync Phone Edition for Polycom telephone device (such as a Polycom VVX phone) that doesn't support encryption.
- A user calls you from a PSTN number.
- You accept the call from the device.
This issue occurs because the Real-time Transport Protocol (RTP) packets that are sent from Mediation server are encrypted.