Originally Posted by KOR
Here's something that might work: Sprint AIRAVE™
If the link doesn't work, search for Airave on their site. I've not used it and am unsure if it will work with other models...
Tmobile has the same sort of thing which is the UMA I had previously mentioned. In their case, they use a modified version of a WRT54G router, most likely with QOS for phone service so you can maintain decent voice quality.