I do most things on a T-Mo cellphone. For long conversations that one would usually do on a landline I have been using Skype (SkypeOut, $36/yr). Since my subscription expires in a couple of days I've been sniffing around to see if there are any better fits out there:
- Skype is not open source, and my workstations are linux. Skype software for linux lags behind Windoze versions and is too bloated/cutesy for my taste.
- I don't use many minutes, so a by-the-minute deal is probably cheaper for me than a flatrate monthly deal.
The best-known SIP client is ekiga, originally a student project designed for Gnome, one of the Big Two linux integrated desktop environments. The clients talk to each other using a SIP provider, a kind of matchmaker. Calls are free from pc-to-pc. There are commercial SIP providers that offer PC-to-phone calling (outbound), which is what I was buying from skype.
The commercial SIP provider I picked was Diamondcard. The cost per minute to the US/Canada is $0.016 (ie, 1.6c/minute). This means if I talk more than 188 minutes a month on Diamondcard it will cost less than Skype. If I talk more than that it would be cheaper to use skype. Should be an interesting experiment.
188 mins doesn't seem like much, does it? But my cell is my main point of contact and I use it about 90mins / month. They don't even make plans that low. I have no idea how people burn through 1000s of mins each month.