A newb with some questions

[zer0t]

I have what is a T-Mobile Dash, it is unbranded HTC early phone. How do I tell if it is unlocked? I have an AT&T sim card in it and it works fine. I want to upgrade from Windows Mobile 5 to Windows Mobile 6 or even better 6.1. I have found the t-mobile windows mobile 6 upgrade, but would like to understand better what that means.

I am not even sure that the HTC titan is the s620 phone, so if it is not please let me know and I will repost in the appropriate forum.

Thanks in advance for any help,
Rob