The steps are very simple, since everything works out of
1. Take off the back lid of the Nexus One and take out the
battery, only then can you insert the SIM card.
2. Slide the SIM card in and then replace the battery. Close the lid and power-up your phone.
3. Once the phone is on, check the right hand corner: you can see that AT&T was recognized as a carrier. If you are wondering about the screen with white dots, this is a pattern security screen: instead of entering a PIN for security, you connect dots in the predefined pattern. We like that feature.
4. Look at the top right – you can see an E icon with arrows, meaning that the EDGE network is available. Again, nothing to configure; it was recognized automatically.
Keep in mind the Nexus One will not have 3G on AT&T network, due to hardware limitations. On the other hand, 3G is available on Nexus if you are on T-Mobile.
5. We tried to set-up visual voice mail, actually knowing that it would fail; see the screens below with the fail message.
Since Google Voice is built in into Nexus One, we will provide a guide at a later date on how to configure the Nexus One on the AT&T network with Google Voice.
Keep in mind that nexus was able to recognize AT&T's voicemail number automatically and after calling that number we did not require to enter PIN number for access. Do not know about you folks but voicemail is so 20th century.