Please help, full signal but cannot ring out!

[VickiAmaya]

Hello,

I have done everything i can possibly think of to get this phone to work. It was my partners old phone, he had the network lock disabled so i could put my payg sim card in it, and since then it has not worked. The phone has full signal and updates the date and time so it obviously has some kind of connection.
We have tried re-installing the operating system, updating the operating system and have browsed the internet pages for help for the past three days with no pervail. The imei is not blocked or anything like that and we have no other idea as to how to get it to work.
Any suggestions will be helpful with this as my partner is willing to get the sledgehammer from the shed to solve this issue.

Thanks in advance

VickiAmaya