Only today I stumbled over an article that was published in April on "TheFeature" titled "Why Skype for mobile isn't a big deal". TheFeature is owned by Nokia and claims to be "the mobile Internet industry's premiere thinking space" according to its own About-page. A promising start. Here is an excerpt from the article:
"There's widespread perception that Skype clients for mobile phones would cause a seismic shift in the mobile industry. But there's a bit of a disconnect between expectations and reality. [..] "Free" on the wired Internet doesn't translate to "free" on mobile. Few wired Net connections are charged on a per-packet basis, while that's still very much the norm for mobile data -- and even many so-called "unlimited" plans have caps that would be difficult to hit with everyday mobile surfing and e-mail, but could be used up by Skype pretty quickly. Skype says its software uses 0-0.5 KBps when idle, or 3-16 KBps when on a call. That's 30 KB per minute when idle or beween 180 and 960 KB per minute on a call -- which on many mobile networks would run up a huge bill quite quickly. "
Wrong. To use the author's own words, there is a bit of a disconnect in his calculations between bandwidth (measured in kbps) and storage (measured in KB) and consequently between his deductions and reality. Multiplying the kbps by 60 does NOT lead to a KB value per minute (as the author has done).
There are 1.000 bits in a kilobit (10^3 bits) and 1.024 bytes in a kilobyte (2^10 bytes), while one byte consists of 8 bits (read Bob Bemer's explanation why a byte is called a byte and why it has 8 bits, he helped inventing it). So to convert from a bit-value to a byte-value you need to divide the bit-value by 8. Hence, 1.000 bits are 125 bytes. So by using the author's figures, a bandwidth rate of 16 kbps for Skype would actually mean transfering 2.000 bytes per second or 120.000 bytes per minute or exactly 117,1875 KB per minute - a far cry from the 960 KB per minute claimed. (Here is a site that easily converts bits and bytes)
Would this still run up a huge bill on a many mobile networks? In Germany, Vodafone D2 offers the UMTS Mobile Connect Card, the tariff with the lowest MB consumption is the Vodafone-Volume packet for 9,86 € per month, which comes along with a 10 MB data volume (or 10.240 KB). That means each KB data volume costs 0,0963 Cents, our one-minute 117 KB call therefore would have cost 0,11 Cents. The pricing of Vodafone's UMTS data tariffs is degressive, 500 MB cost 110,20 € per month. Do the math yourself.