The F252 and F256 were raplacements for the ZTE F850 and F851 Next G mobile phones. These phones were improved versions of the F850 and F851 and were inexpensive Next G mobile phones. The front pf the phone was changed, with a metal sheet over the top, and the device was slightly more curved rather than a square shape of the preceding models.
The F252 and F2526 were able to be used as a 'mobile as a modem' which was a touted feature of the device and the NextG network and was a 3.6Mbps HSDPA handset.