Grandstream DP750, Incoming works, 503 on outgoing

Hey all. Trying to setup a Grandstream GP750 with my service. It registers fine as seen both on the device itself and on my account. I can receive calls fine, but I am unable to dial out. I get a 503 error on the phone as soon as it tries to dial a number. I’ve followed the wiki instuctions for the GP750, but even with that I can’t dial out. I’m sure it’s something dumb, but I can’t see what it could be. Any pointers?

Hello @ChinookTX,

Are you using SIP TLS? If no, do yourself a favour :blush:. If yes, are you sure you did setup the SRTP setting correctly (and “Force” it)?

I had to setup a DP750 a few weeks ago and I had to really dig in the menus here and there to get everything right. But I have no device in hand (nor a good memory) to help out.

I can only confirm that it works (I was using TLS/TCP) but I have to find the right option (especially the SRTP one I believe).

Kind regards!

Thank you for your response. I am using SIP TLS yes, and I configured my subaccount to encrypt calls, as well as my base station with TLS encryption. I got fedup this morning and deleted the sub-account and created a new one. It worked first time… There must have been something I changed way back that didn’t play nice with the DP750.

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Yes, it was not the easiest device to configure, but it finally worked. I am glad you could figure it out, somehow. :blush:

Kind regards.