Missing calls issue

[pjovp]

Hello,
I've been having missing calls over the past days.
I get a message saying that someone had just tried to call me when my phone is connected.
People say then when call me it says my phone is disconnected.
Anyone had the same situation or you know what is causing it?
Thanks

 

[pjovp]

Also, its showing my network name and 3G in front of it.
This is something that just appear a couple of days ago and after I connect to the internet using data connection.
Can it be related?