There is actually a hidden "Testing" control panel on the Motorola Atrix 1.
Accessing it is very simple and does not require root access, simply go to the dialer and type *#*#4636#*#*
Doing so, will bring up the menu pictured below:
Under "Phone information," you can do things like forcing the phone to only connect to 2G networks or 3G networks by setting the preferred network type. If you are more interested in this, here is a full guide.
Finally, to make things easier, you can actually add this number to your contacts list: