Here are the results of my speed test using the X70’s 3G modem with an AT&T SIM in the heart of Downtown Los Angeles. Not bad. Voice calls also work as reported by Chippy of UMPCPortal (See Voice Calls on X70). Here are the settings I used:
Viliv support’s S5 Premium 3G Activation through AT&T tells you how to set up Viliv’s Mobile Partner software. Mobile Partner on the X70 evidently is a bit different than on the S5, but close enough.
Hope this helps!