LinkedSIP opens soon. Sign-up, payments and calling are not open yet, and the rates shown are examples.
Sign inSwitch calling on
Switch calling onSign in
500
5xx Server error, RFC 3261

SIP 500 Server Internal Error

SIP 500 Server Internal Error means something broke inside a server on the call path. It is not caused by your settings, though odd requests can cause it.

Who sends it
The SIP trunk
When
Placing the call (INVITE)
Retry?
Once. If it repeats for the same destination, report it.
The caller hears
A failure tone straight after dialling.
PBXYour phone or PBX
SIPThe SIP trunksends 500
☎The called side
FIX

What causes 500, and how to fix it

500 means something broke on a server in the path. It is not caused by your settings, though an unusual request can sometimes trigger it.

  1. 1
    Most common

    A software fault on a proxy or gateway in the path.

    Retry once. If it repeats, note the time, the number and the Call-ID and contact support.

  2. 2
    Sometimes

    An upstream route failed and its error was passed on as 500.

    Try another destination. If only one fails, report that destination with the time and Call-ID.

  3. 3
    Sometimes

    An unusual header or message body triggered a bug.

    If you changed PBX settings recently, such as custom headers, undo the change and test again.

  4. 4
    Rare

    A service-wide problem at the provider.

    If every call fails, check the provider's status updates before changing settings.

LOG

What 500 looks like in a SIP log

SIP/2.0 500 Server Internal Error

Capturing one: reading the SIP log.

SIP response
SIP/2.0 500 Server Internal Error
Via: SIP/2.0/UDP 203.0.113.10:5060;branch=z9hG4bK-74bf9
Call-ID: [email protected]
≠

Not to be confused with

500, 503, 502 or 504?

503

Service Unavailable

Capacity or maintenance: the server is fine but cannot take the call now.

502

Bad Gateway

A gateway got an invalid response from the next server.

504

Server Time-out

A server timed out waiting for the next one.

FAQ

SIP 500 questions

Is SIP 500 my fault?
Almost never. It is a server-side failure. The exception is an unusual request, such as a custom header, that triggers a bug; undo recent changes if the error started after them.
What should I send support for a 500?
The time of the call, the number dialled and the Call-ID from your PBX log. That lets the provider find the exact failure.

Not 500? Look up another code.

The full list: SIP response codes. 500 again and again? Check your SIP trunk configuration.

All SIP codesFind a fault by symptom