I am going to greece for a month and I wanted to use some prepaid overseas plan with my phone. T-Mobile USA (Great Company!!) gave me the unlock code for my phone as I was a paying customer for 3 months. I input the code as per their directions and then phone says sim unlocked. So I put a friends Cingular Nokia 6180 Sim card into my Moto V188 and the phone started up and showed Cingular for the provider name and showed 3 bars of signal strength. However when I tried to make a call it said something like call error.

Is my phone completely unlocked or is it unlocked as long as I don't try to put a USA sim card in it. Is it probably good to go when I go overseas or is something screwy going on.

Thanks much for any help or explanation as to why my little experiment didn't work ... John

It is possible that you're original network put a block on the phone on the network side, I've seen it happen a few times after a contract's run out.
In which case, changing that is illegal under UK law, punishable by 3 years and £10,000 minimum. And you'd likely need access to the network black list... Not an easy task! lol

However, if the phone accepts the SIM card and at least tried to get signal, it's unlocked.

Yeah I figured everything was OK. It says sim ulocked where it used to say sim locked.

I dunno what you mean by network block. Tmobile will only unlock their phones you get from them that you have an account for 3 months at least. Also you need to be paid up to date or whatever.

Networks occassionally block their phones if they feel you've not kept up any contracts taken out with them.

However, unfortunately, I don't have a solution for your problem. Sorry.