Grandstream UCM6302 WAVE App Call declined



I have a UCM6302 phone system in my network. The Wave app was activated on the extensions and has been working for about a year. However, for the past few months, phone calls have not been going through properly. I can make internal calls with my smartphone and laptop without any issues. But when I call an external phone number and the called number answers, the call gets disconnected. The log file of the Wave desktop app shows error code “603” (reason: Decline). UCM firmware version is and Wave version is


FW is a beta version, it should not be used in production (beta versions may contain bugs or inaccuracies),
the latest stable FW is, and any problems must be reported on this version, in any case below you will find the Grandstream Support link, a feedback would be appreciated here once the problem has been found and resolved, so that it can possibly be useful for others forum users:


Dear user,

Thank you for using the UCM63xx device! It looks like there are some internal errors in the UCM, such as dial plan rules, but we cannot locate this issue unless we can obtain the syslog. Please kindly ensure that the PJSIP Log option and PBX Log option are enabled before downloading the syslog. You can also send the remote access of the UCM6302 to us for troubleshooting. Thanks for your testing!

Thank you!