SIP 488 Not Acceptable Here
SIP 488 Not Acceptable Here means the far side cannot accept the call's media settings, most often because no audio codec in your offer matches what it supports.
- Who sends it
- The called side
- When
- Placing the call (INVITE)
- Retry?
- Not until the codec or media settings are changed.
- The caller hears
- A failure tone straight away, or the call drops at the moment it would connect.
What causes 488, and how to fix it
488 means the two sides could not agree on how to carry the audio. Codec mismatch is the usual cause, followed by encryption or transport mismatches.
- 1Most common
No codec in your offer is supported on the route, for example only Opus or G.722 is enabled.
Enable G.711 (PCMU and PCMA) on the phone and the PBX, alongside any others you want.
- 2Most common
Your phone requires encrypted media (SRTP), and the route does not offer it.
Set media encryption to optional or off unless your account says the route supports it.
- 3Sometimes
A fax or a transfer changes the media mid-call and the new settings are refused.
For fax, check that T.38 or G.711 pass-through is set the same way on both sides.
- 4Rare
An unusual packet time or media attribute is rejected.
Use the default packet time of 20 ms and remove custom media settings.
SIP/2.0 488 Not Acceptable Here
Via: SIP/2.0/UDP 203.0.113.10:5060;branch=z9hG4bK-74bf9
Call-ID: [email protected]
Warning: 304 sip.linkedsip.com "Media type not available"Not to be confused with
488, 606, 415 or 403?
Not Acceptable
Not acceptable anywhere: no device of the callee would accept the media.
Unsupported Media Type
The body format itself is not supported, not just the codec choice.
SIP 488 questions
What is the most common cause of SIP 488?
Can encryption cause a 488?
Not 488? Look up another code.
The full list: SIP response codes. 488 again and again? Check your SIP trunk configuration.