i spent quite some time researching my issue and found out that there is a bunch o people with this problem. The downside is, none of the recomended fixes seem to work.
Description: I recently got a S4 active i9295 with stock rom. Everything clean, nothing custom on it(i belive). For a couple of hours it worked like a charm, then, when i want to call someone, the transition from contacts to dialing screen lags a bit and then it goes into dialing and thats about it. Nothing else happens from there on. I loose signal and it keeps showing that it dials (i let it like this for about 15 minutes and nothing happend). I cannot end the call, it remains stuck in "dialing" mode, i can use all the other functions though. After a restart it works again. Same goes for sending SMS. The icon spins and spins but never sends the SMS, only after a reboot. Also when someone calls me, they get a "no answer" signal and my phone just looks ok, like normal standby but when i want to call back, it freezes at dialing.
I tried 3-4 different stock 4.4.2 roms, hard reset, wipe/clear cache, safe mode... It works fine for 15-20 calls/2-3 hours and then it does it again. After that point it only gets worse and it happens more frequently.
Any ideas on what could cause this or how to permanently fix it? Unfortunately, returning the phone is not really an option.
Thanks to all, best regards.