I was so excited about getting a unit of S5 Premium 3G, which has 3G modem embedded model of viliv. When I first got the unit, I was not just able to wait to go to wireless carrier store because I tried to call Tmobile and AT&T sales person but could not get enough explanation about my S5 Premium 3G 3G data service activation. When I spoke to T mobile sales person over the phone, all I was told by Tmobile was to sign a data service of 3G and I try to see if my S5 Premium 3G unit is working through Tmobile 3G data service. I asked him to check what kind of Tmobile 3G data service is offered. Actually I was hoping he would mention that Tmobile 3G data service is using EVDO. But I was not able to hear that at all. Next day I went to a Tmobile operating store nearby where I live. Actually I live cross the street from UCLA, where many college students and office workers are around. The sales person at a Tmobile store did not say any thing about EVDO, said that I better wait or come back to see a person who might know about their 3G data service details. I decided to stop exploring Tmobile as I already knew Tmobile uses EVDO, which is not compatible with viliv S5 Premium 3G. And I tried an AT&T store and had a pretty much similar experience there. And I was told by a sales person at that AT&T store I should try to check a cell phone store cross the street. That was the place where I was able to hear that I only need to get an AT&T 3G data service activated and get an AT&T SIM card. But this store owner also did not know what kind of data service package offered by AT&T. I signed up a unlimited 3G data service for $29 per month with 12 months contract. The regular SIM card was inserted into a slot inside of battery pack of viliv S5 Premium 3G. The following is the procedure I did to get 3G data service. First, I opened "Mobile Partner". Click "Tool" Then Click "Option" Open the "Profile Management" tab. Set up a new profile with the following process. Name: AT&T APN: wap.cingular Proxy: leave blank Port: leave blank Username:WAP@CINGULARGPRS.COM Password:CINGULAR1 Server: leave blank MMSC: http://mmsc.cingular.com MMS Proxy: wireless.cingular.com MMS Port: 80 MCC:310 MNC:410 (note. this could also be 310, 41 or 15) APN Type: leave blank