180 1xx Provisional RFC 3261
SIP 180 Ringing
The called device is alerting the user. The caller normally plays local ringback tone unless early media arrives.
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Common causes
- The destination phone or softphone is ringing.
How to fix it
- If the caller hears silence instead of ringback, the caller's device may expect 183 with early media. Configure the far end or SBC to send 183 + SDP, or make the caller generate local ringback on 180.
Seeing 180 on calls through a router or firewall? Check that SIP ALG is disabled. It causes a surprising number of SIP errors. Read why.
About 1xx responses
The request was received and is being processed. The call is not finished yet.