If Grandma (or you) like your IOP the way it is but want to use another ISP now that AT&T has dropped you, here is what is possible, at least with a V5 IOPENER.
Get a bootable laptop drive that boots to dos. The drive has to be one of those that will co-exist with the sandisk. Some drives bump the sandisk off line and that won't work.
On the drive you need a copy of the any ISP earthink image and dolly.
Take out the bios chip, reflash it to the V531 image, or pop in one of mine. Earlier versions will probably not work. None of the images I tried would work once the unit was updated. The AT&T bios would not boot the earthlink sandisk image.
Using a "flipped" cable like the ones I sell, or any of the ones used to boot from a drive on an IOPENER, hook it to the IOP and the drive and boot to the unit to dos. Run dolly to copy the earthink image to the sandisk:
DOLLY C:\EARTHLINK.IMG HD129:
Was the command I used where earthlink.img was the 16meg earthink image and HD129: was the sandisk address.
Remove the drive cable & button it up. Be sure to cool the cpu. I put the heat sink back in place while I worked.