What do telephony and error codes mean?

Overview of sipgate telephony error codes (401, 403, 486, etc.) with explanations and troubleshooting tips.

The following error codes occur most frequently:

401 Access credentials incorrect	The identifier (SIP ID) or the password (SIP password) is incorrect.
404 Phone number unknown	The phone number does not exist, is not assigned to a line, or is not configured on the recipient's device/telephone system.
486 Busy	The remote party reports that the subscriber is busy.
487 Hung up	The usual signal when the remote party hangs up.

Other commonly transmitted codes:

100 Call forwarding	An attempt is being made to connect the call. This code is part of the normal call setup process.
180 Ring signal	The ringing is signaled by the called party's device.
183 Connection setup	The connection is currently being established. A ringing tone or announcement may be heard.
200 OK	The call was answered, or the device has registered with the server.
301 Permanently forwarded	A permanent forwarding to another destination is set up.
302 Temporarily forwarded	A temporary call forwarding is set up on the called party's phone.
400 Invalid request	The request contains incorrect parameters. This usually means that you entered data into the wrong field in the phone configuration.
403 Not allowed	The subscriber is not authorized to make this call.
407 Proxy authentication required	For outgoing calls, the phone must authenticate itself to the server.
408 No response (Request Timeout)	Usually occurs when your router or firewall partially or completely does not forward data packets to the phone.
480 Temporarily unavailable	This is received, for example, when the called party has activated DND/Do Not Disturb.
481 Call does not exist	Occurs rarely, mostly when a status message has not reached its destination.
482 Loop routing detected	Loop routing often created by forwarding (A ➔ B ➔ A).
488 Call attempt not allowed	Occurs when the codec used by the device, the encryption, or transmission method (e.g. video) is not supported.
500 Server error	General server error.
502 Wrong gateway	The gateway (server) in the SIP request is incorrect.
503 Service not reachable	The server's SIP service is temporarily unavailable.
603 Rejected	The remote party rejected the call. This can happen manually or automatically.