| Description | This article describes how to overcome a situation where a SIP call cannot be established and the destination party returns a SIP message containing 'Status: 488 Not Acceptable Here'. |
| Scope | FortiGate. |
| Solution |
If a call cannot be established and the destination phone returns a SIP signaling message containing the SIP status code 488, which stands for 'Not Acceptable Here', it is an indication that a mismatch exists between the phone and the party initiating the call in regards to the audio/RTP configuration settings: one of the sides is requesting the usage of SRTP (Secure Real-Time Transport Protocol, RFC1711).
Packet capture in Wireshark will show on the phone SIP response:
The SIP/SDP message will contain the line: 'Status-Line: SIP/2.0 488 Not Acceptable Here The issue is not a FortiGate issue: it is a phone/PBX setting issue. To allow the call to be successfully established, either disable SRTP on both parties or enable SRTP on both parties.
Related article: Technical Tip: VoIP and SIP configuration and troubleshooting resource lists |
