Default Help. No sound on calls

Hi

Having a problem with my S4

When making calls i cannot hear anything, other person can also not hear me.

Have tested the speaker in samsung test settings and it works fine

If using viber or skype etc then it works fine.

Running 4.4.2 Foxhound Rom,

Have tried a reflash and also flashing a new modem with odin.

Can anyone help

Thanks