calling wont work directly

[keikeichris]

Hi there I have got this xperia T for a few months now.

And recently, when I try to dial, after pressing 'CALL'  the screen turns dark and wont dial at all.

But after like a minute it then dial, which is a huge problem and it has costed me so much minutes when I was not aware the call was made a minute late, being in my pocket. PLease help...

Much appreciate !!

[Uliwooly]

Double check if there's anything near or on the proximity sensor 

backup your contacts and try

settings > apps > all > phone > clear data/cache > restart your phone