I picked up a Nexus One last week from someone who got it from the TED Conference. Apparently Google also gave out a SIM card with a month of service on T-Mobile. When I go to Settings / Call settings / Voicemail settings and the number shows the number that was given at the TED Conference, which is the old SIM. I keep changing it to my phone number as I am using my SIM. It takes the changes but if I reboot the phone, it reverts back to the old number. Any ideas?