Hello again
Both Yahoo, MSN, and Skype can make calls to Mobile and Residential phones (I would call or contact each company to check and see about your country first)
Go to
http://www.speedtest.net/Tell us what up speed, and what down speed you have.
If you have at least 300KBPS, then I would say that 256KBPS would be the best for your internet connection (providing you are limiting your internet browsing while you are making a call)
If its below 300KBPS, then I would recommend using 128KBPS.
The higher KBPS rate (kilobyte per second) the better your connection is.
(Note: Connections, and every data transfer are also measured not only in Kilobytes, but bytes, megabytes, and gigabtytes. )