I’ve been experimenting with SipPhone for some weeks. They offer a service that connects your internet phone to a standard telephone number  for approximately two cents per minute.  Like a pre-paid phone card or pre-paid cell service, you can purchase a block of time for $10.00 minimum. When you make a call a voice comes on the line telling you how much time you have available for the call.  I’ve been using the service when traveling to client sites. Once I connect my laptop to the client’s network, I can fire up EyeBeam (the XTen software phone)  on the laptop.  EyeBeam is configured to use SipPhone as the telephone provider. 

The EyeBeam is pretty spectacular; it includes the ability to do videoconferencing (which I haven’t even gotten around to trying yet…) However, there are numerous free softphones that you can download, including one from SipPhone itself which is a go-branded version of the X-Ten softphone.

Once the software is runing on the laptop the phone will automatically attempt to register with the SipPhone directory service, and you’ll see a message “logged in — enter phone number” and a display of your own SipPhone phone number, which is usually (?) in the 747 area code. (You can buy a customized “viritual” phone number too, in a number of different area codes.)

Other SipPhone users can dial your SipPhone number, and the call is completed over the Internet. This costs nothing. Only if you connect to a regular phone, do the SipPhone charges apply.  

Several issues as far as the calls are concerned:

1. A broadband connection is required. Both Verizon DSL and Adelphia cable seem to work fine.
2. The service appears to be much more reliable, with better voice quality, and fewer delays, in the mornings.
3. Depending on internet traffic, and presumably local LAN traffic on your office network, the software phone may not even register with SipPhone Central, and you will be unable to make calls.
4. At its best, voice quality is identical to that on a standard telephone.
5. If both parties talk at once there is a “collision”. As such, the service appears to be less than “full duplex”. 
6. There is sometimes delay between the time you speak, and the time that the other party hears your voice. 
7. The time to connect the call, that is, between the time you dial a number and the time it starts ringing can sometimes be a minute or more.
8. International rates are great. 4 cents/minute to Germany, for instance.

Note that items 1–6 are not necessarily related to SipPhone per se. I’ve had similar experience with Free World Dialup.

Alternatives: 

Maybe Skype+SkypeOut.   Phonecard minutes from Costco phonecards. (2 cents/minute)  Cellphone minutes.