N900t ¨not registered network¨

The phone came into my hands from a client, who apparently suddenly it stopped working.

IMEI and Baseband is Ok. Network Signal is ok, but not resgistered on network.

Androide Version: 4.4.2.
Modem: N900TUVUCNB4.

I try this:
– Wipe Data and Factory Reset from Recovery.
– Write QCN from another working Phone, and still the problem.
– Wipe EFS/NVM and Write Cert from another working phone and nothing.

any suggestion please