Troubleshooting Tip: An SIP call cannot be established and the destination party returns an SIP message containing 'Status: 415 Unsupported Media Type'

[ACARIMO]

Description	This article describes how to resolve a situation where a SIP call cannot be established and the destination party returns a SIP message containing 'Status: 415 Unsupported Media Type'.
Scope	FortiGate.
Solution	When Implementing a VoIP/SIP solution, the IP phones and the PBX/VoIP provider need to use the same CODEC for a particular call - and the same is valid for the interconnection between a PBX and a VoIP provider. When the calling party attempts to establish a call using a CODEC that is not supported by the remote party, the call will not be established and the calling party will receive a SIP signaling message containing the SIP status code 415, which stands for 'Unsupported Media Type'. The CODEC mismatch is not a FortiGate issue: it is an implementation issue of the VoIP/SIP solution. The solution is to use the same set of CODECs on the IP phones and on the PBX/VoIP provider. Related article: Technical Tip: VoIP and SIP configuration and troubleshooting resource lists