Yes, I’ve had such issues myself!
It’s not just the PSU itself - the connections to the module (especially ground) need to be absolutely “solid”
Example: viewtopic.php?f=123&t=5693&p=23827&hilit=vbatt+line+too+narrow#p23826
This is because all GSM devices have a very high supply current peaks - Wavecom quote over 2A! 
Edit:
Just noted that I have already mentioned “Module Grounding” in an earlier suggestion in this thread!