HTTP 402 – Payment Required
w3.org
w3.org
http://www.ietf.org/rfc/rfc2068.txt
Nothing new here.
So call goes from TelcoA, to Reseller1. Reseller1 cleverly returns 402. TelcoA stops and doesn't failover, returns error to customer. TelcoA is unhappy, because they wanted to continue the call to Reseller2.
Source: I work in wholesale telecom and this is exactly what every larger customer asks for. They must get a 5xx error (sometimes a 503 specifically), or their side won't continue hunting the call.
402 and all the other fun stuff might be used in a more pure SIP environment, but I doubt it's used in any sort of significant % of actual SIP deployments. Actually, just like most of the spec. It's either confusing, useless ("Retry-After: 300 (I'm in a meeting)", or a security hole.
It's very helpful as a provider of services to Shopify stores to know 'this prospect may not pay'. The average shopper doesn't know HTTP codes too, so it avoids tarnishing the shop's reputation if it was just an oversight.
So a 3xx error.
Bitcoins could be the solution here.
When it still was all rage :)
A real 410 would obviously be even worse, but that won't usually happen by accident. When my server/app crashes and I'm working on restoring the configuration, in the meantime, it will usually show a 404. And that's bad.
Handle youtube CAPTCHAs (402 errors) gracefully: https://github.com/rg3/youtube-dl/issues/154
Speaking from experience... -_-;