Please keep in mind that these are guidelines as every place uses the sip code differently.
4xx - The call could not be completed
The call request could not be carried out. The cause may be the call itself, the number dialled, your account settings, or how the request was formatted.
400
Bad Request - Inbound & Outbound
The call request could not be understood because of malformed syntax in the request. Ensure that there is no empty spaces or invalid symbol. Verify your device’s dial plan is outputting digits in a format the SIP provider accepts.
401
Unauthorised - Inbound & Outbound
The call request requires authentication. This response is issued by the receiving server, unlike 407, which is issued by a proxy server in between.
403
Forbidden - Inbound & Outbound
The request was understood, but the platform can’t complete it. This may be because the destination is not allowed to receive this type of request, or because your account has that specific destination blocked.
Forbidden – Invalid CLI - Outbound
The caller ID (CLI) presented on the outbound call is not valid or not permitted.
Forbidden – Premium Destination - Outbound
The number dialled is a premium-rate destination that is not enabled for your account. You can turn that on in the Voice Management App.
404
Not Found / Route not found - Inbound & Outbound
There is definitive information that the number dialled does not exist at the domain specified in the request. Or for inbound CM.com host this number it but it is not assigned to you, or you have not yet configured it in the Voice Management App.
405
Method Not Allowed -Inbound & Outbound
The method (the type of request) is understood, but is not allowed for the address it was sent to. (Compare with 501, where the method is not recognised at all.)
406
Not Acceptable - Inbound & Outbound
The request can only be answered in a way the caller said it can accept. There is a mismatch in what each side allowed to use.
407
Proxy Authentication Required - Inbound & Outbound
Like 401, but the credentials are required by a proxy server in between rather than by the final destination. In an outbound call our SBC will be the proxy.
408
Request Timeout - Inbound & Outbound
The destination could not be reached in time. No answer came back quickly enough to continue setting up the call. could be network issue, retrying later will often fix.
410
Gone - Inbound & Outbound
The called part is not reachable with this number anymore. Please use a different number in this case.
413
Request Entity Too Large - Inbound & Outbound
The receiving server is refusing the request because its body is larger than allowed. Please reduce the size of your SIP request.
414
Request-URI Too Long - Inbound & Outbound
The receiving server is refusing the request because the address (URI) in it is too long to process. Please check the user part (The phone number) of your request URI.
415
Unsupported Media Type - Inbound & Outbound
The message contains content in a format the receiving server does not support. Please check your codec set.
416
Unsupported URI Scheme - Inbound & Outbound
The receiving server does not recognise the scheme (the part before the number) in the address. please check your scheme and check if it doesn't start with the prefix such as tel: or sips: instead of the standard sip:
420
Bad Extension - Inbound & Outbound
The receiving server did not understand a protocol extension that the request marked as required.
421
Extension Required - Inbound & Outbound
The receiving server needs a specific protocol extension that was not offered in the request.
480
Temporarily Unavailable - Inbound & Outbound
The destination was reached, but was not available to take the call right now. Reason to get 480 could be:
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Device is on Do Not Disturb mode, powered off, or experiencing network connectivity issues.
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By call forwarding the device being forwarded to is not in the correct format or is busy.
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A codec disagreement between servers could also result in a 480.
482
Loop Detected - Inbound & Outbound
The call was being routed in a circle and would never reach a destination, so it was stopped to prevent endless call looping.
483
Too Many Hops - Inbound & Outbound
The call passed through too many servers on its way (the hop limit was reached), so it was stopped. This is usually a sign of a routing loop.
Please check option of the max-hops in the pbx. Default should be 70.
484
Address Incomplete - Inbound & Outbound
The dialled address appears to be incomplete (too few digits for example), so it could not be resolved to a destination.
485
Ambiguous - Inbound & Outbound
The dialled address could match more than one destination, so it could not be resolved to a single number.
486
Busy Here - Inbound & Outbound
The destination was reached, but is not willing or able to take additional calls right now. Often if the Callee declines the call this can occur. Comparable with 600 ‘Busy Everywhere’, but that one means no other endpoint such as voicemail can take the call either unlike 486.
487
Request Terminated - Inbound & Outbound
The call was cancelled by the caller before it was set up. For example, the caller hung up before the destination answered.
488
Not Acceptable Here - Inbound & Outbound
The destination was reached, but some aspect of the call was not acceptable at that specific endpoint. Like the media type being incorrect or unsupported.
5xx - A server in the call path hit a problem
Something went wrong on a server rather than with the number you dialled. The exception is the two 503 limits, which are about your own account's traffic settings.
500
Server Internal Error - Inbound & Outbound
A server hit an unexpected problem and could not complete the request.
501
Not Implemented - Inbound & Outbound
The server does not support the functionality needed to complete this request. (Compare with 405, where the function is recognised but is not allowed for that address.)
502
Bad Gateway - Inbound & Outbound
While passing the call along, a server received an invalid response from another server in the chain.
503
Service Unavailable - Inbound & Outbound
In general this means a server is temporarily overloaded, under maintenance, or unable to process the request.
Service Unavailable – CPS Limit - Outbound
You are sending more calls per second than your account is allowed to. CPS is the rate at which you start calls for example a CPS limit of 2 = 2 calls/second = 120 per minute = 7,200 per hour. Everything above your limit is blocked. Note that blocked calls still reach CM and consume resources, so it's important not to rely on us to absorb the overflow. Stay within the CPS limit set in the Voice Management App and spread your traffic out over a longer period rather than sending it in bursts.
Service Unavailable – CC Limit - Outbound
You have reached the maximum number of calls happening at the same time that your account allows. CC limits exist to protect capacity on our platforms. The limit is set per SIP account in the Voice Management App, and only answered calls count towards it (counted per platform, per SIP account).
504
Server Timeout - Inbound & Outbound
One server in the chain waited for a reply from another and gave up before it arrived.
505
Version Not Supported - Inbound & Outbound
The server does not support the version of the SIP protocol used in the request.
513
Message Too Large - Inbound & Outbound
The server was unable to process the request because the message length exceeded its capabilities. Please check your message.
6xx - The call was refused everywhere
These are global refusals. The destination was reached and the call was definitively refused, so trying another route or endpoint to this endpoint will not help. (Compare with 4xx codes, which apply only to one attempt or location.)
600
Busy Everywhere - Inbound & Outbound
The destination was reached and is busy. Unlike 486 Busy Here, this means the destination's system knows there is no other endpoint (such as voicemail) that could take the call.
603
Decline - Inbound & Outbound
The destination was reached, but the called party actively declined the call (or cannot take it) and gave no alternative. Might not accept the calls anymore.
604
Does Not Exist Anywhere - Inbound & Outbound
CM has reliable information that the dialled number does not exist anywhere. A stronger, global version of 404 ‘Not Found’.
606
Not Acceptable - Inbound & Outbound
The destination was reached, but some aspect of the call was not accepted, for example the session description, the requested media, the bandwidth, or the addressing style. This is the global version of 488 ‘Not Acceptable Here’: a 488 rejects the call at one endpoint (another route might still work), while a 606 means it is unacceptable everywhere.
607
Unwanted - Inbound & Outbound
The destination has indicated they do not want calls from this caller. If this happens often please contact Support for help.