Just thought I'd share...
https://www.myxlink.com/index.aspx I just bought one of these and wondered if any other forum members have ever heard of or tried this device.
You pair XLink with your cell phone (it supports pairing up to 3 phones at a time) via Bluetooth and it allows you to plug in a standard telephone and make calls through your cell. If you've got multiple cell phones paired, you can even select which one you want to call out on by dialing a special key combination.
While I'll admit I've only been using it for a day, I've been pleasantly surprised with how well this thing actually works. I've got it paired with my Samsung Galaxy S and connected to a CO port on my Panasonic TDA50. No, it's not a POTS line, but call quality is excellent and volume is great...tons better than using my cell phone by itself.
I know there are other devices like this out there, but most others I'd researched seemed to have tons of negative reviews or had to be purchased from a cell carrier which meant paying an extra monthly fee. Other than a couple of tech magazine reviews, I couldn't find much information about XLink before purchasing it, but figured I'd take the chance and have been very satisfied with the device so far.
Hopefully this information might help someone out, and if you've tried XLink, I'd be very curious to hear how well it's worked (or hasn't worked) for you.