Originally Posted by da_undead
Updating us with this info is much appreciated.
As you know, I am facing the same problem as is being described by you. Luckily it is still under warranty.
In the service centre they have flashed a rom with modem V15 2013/05/27 which apparently is the only single modem that works with my phone.
I migrated the modem.img file from the rom to slx rom and it works like a charm.
Later I realized the V15 was also present in Stympy's modem's thread
1 month ago I tested all modems in Stympy's thread dunno if it wasn't there 1 month ago I guess I missed it.