C25

[otenboy]

I have a Siemens C25 phone. It was working in another country whose provider is dual band (900/1800). It can switch from GSM900 to GSM1800, but when I go to another country whose networks are mostly GSM1800, it can detect available networks (including network of SIM card in that country) but cannot register to such network. Is it possible that the previous service provider that I bought the phone with did a network lock (meaning it will only work with this provider)? The phone is not asking for any security code or displays "SIM card rejected" or any other message. The only thing is that it cannot register with the network of the SIM card inserted.

Please help. Thank you.