It's the end of 2014 and I have the same issue with my OnePlus One phone. Did a factory reset, installed nightly builds, etc. no luck. It must be my micro sim issue.
Yeah I think it's my device. Today, my friend and I swapped our micro sim cards to test a phone call (we have the same phone model and same carrier/APN settings). My friend's phone was able to make a phone call with my micro sim and I still wasn't able to with his sim. So we came to a conclusion it has something to do with the hardware antenna. The issue I'm having with my phone is when the network type is UMTS, this is when the calls don't go throught. When it's on HSPA (H+), it works. Thing is my phone always go to UMTS and rarely in H+ while my friend's phone always go to H+ without a problem.
I'll request a RMA for my phone.
Thanks for your input!