How to get MMS working on an unlocked AT&T Lumia 640 LTE on Koodo network?

[ma678]

I got a Lumia 640 LTE from WM last week and got it unlocked from AT&T. Later on I undebranded it, flashed TMobile ROM, and use it on Koodo (a Telus sub) in Canada. For some reason, I cannot send or receive MMS on it. I am sure I entered APN for both internet and MMS following instructions correctly. Does TMo hard lock its APN settings in its FW? Is there any way I can unlock its APN settings and get MMS working?

Thanks!

 

[Arc Angel 100]

I have this issue with my dual sim 640 on MTS Allstream as well.
I can't send a text to an e-mail address nor send a picture text or video text either.

receiving was hit or miss too (mostly miss).

 

[vhl71]

I also have a At&T Lumia 640 unlocked phone. Using on Koodo without any issues. But I didn't do any debranding. Didn't do sny apn settings manually. Everything worked as soon I put in my sim.
May be your issue is related to TMo firmware

Sent from mTalk

 

[ma678]

I also have a At&T Lumia 640 unlocked phone. Using on Koodo without any issues. But I didn't do any debranding. Didn't do sny apn settings manually. Everything worked as soon I put in my sim.
May be your issue is related to TMo firmware

Sent from mTalk

It worked after I manually set up APNs for LTE and MMS. The weird thing is I am unable to send/receive MMS if wifi is on. Once I turn off wifi, MMS goes through without problem.