A. My fiancee and I recently ran into this problem. We were at a conference and wanted to access the Web. T-Mobile hotspot access is included as part of the phone plan. After much searching of the T-Mobile Web site and phone calls, we found the answer. The username is the 10-digit mobile phone number, and the password is the last four digits of your social security number. On first logon, you'll be prompted to change this password, but that's optional.