Error code 511


When i make a call to cell number, give me an error- call release [511]
What is the problem.


does your server support to dial a cell phone number? you can enable the Syslog as following setting, then use the capture tool to capture the logs so we can take a look what’s the real problem:

(you can use as the syslog server, as it’s not exist, but the device will still send syslog to it, and the capture tool will capture all the data the device sends, this way you don’t need a valid syslog server but still able to get the syslog)


Hi there, I get this error message also. Very seldom it works, but 99% I cannot dial out to any phone number (German Telekom). So this error 511 must be known to Grandstream. And I do not know what a syslog is and how to deal with it.


hi @Shawn-GSSupport424,

I try to say to you too,

The Links for DECT DP firmware are missing on the Firmware GS page


those error code are SIP standard:,
511 is a server side error.
You can see my comment in previous, the Sylsog setting is at Web UI -> Maintenance -> Syslog, just configure the exactly same as my screenshot. Then go to Web UI -> Maintenance -> Packet Capture, click the “Start”, then you make a call to any phone number that you would like to test. once you see the 511 error. hangup the call. go to the Packet Capture, click the “Stop” button, then click the “Download” button. you will get a network traffic packets capture. You can check it yourself, or provide it on the forum, or use it to file a ticket at:, with this debug information, people will be able to help you.


OK thx I tried and it records but I cannot open that file…however at the moment it works but I cannot hear the person calling but the person on other side can hear me. What is this error about?

The code 511 is not listed in your link?


Hi check this out: