402 4xx Client error RFC 3261
SIP 402 Payment Required
Reserved for future use, but some carriers and providers use it to signal an empty prepaid balance.
Typical Q.850 / ISDN cause: 21 (Call rejected)
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Common causes
- Insufficient credit on a VoIP account (provider-specific use).
How to fix it
- Top up the account or check billing status with your provider.
Seeing 402 on calls through a router or firewall? Check that SIP ALG is disabled. It causes a surprising number of SIP errors. Read why.
About 4xx responses
The request has a problem or cannot be completed at this server, usually because of something on the requesting side or the target user.