Uninterruptible power supplies for smaller devices? (no replies)

After 15 years of monthly AT&T bill ending up at $107 including 756Kbps internet connection.... (deep breath) they had a lower cost plan that's 5Mbps connection and includes a modem any standard phone plugs into for $72-Mo for a year until it goes up $10. The router is an Arris BGW210-700

So I thought to ask, if there is such thing as an uninterruptible power supply that goes between the wal wart and the router so that if the power goes out a smaller device could output I think 12 volts instead of those large units that probably cost more, but I don't know.

Then again, if the power goes out I don't think the power consumption would be high at all, and 10 minutes of phone and 10 minutes of internet should get me through most power outages.

Thanks for your consideration, brainstorm, comment :-)