Hack23.Round Call Time to Your Advantage

Hack 23. Round Call Time to Your Advantage

By understanding how Skype figures the cost of your call, you can save money.

Works with: all versions of Skype.

Over the long run, the way in which call times are rounded can make a big difference. This is particularly true if your call volume is large, as it might be for medium to large organizations that use SkypeOut.

To illustrate why, consider this example. Ten thousand calls are made with a random duration of between 15 and 60 seconds. First, calls are rounded up to the next 6-second interval, and then calls are rounded up to the whole minute. Using just one set of randomly generated data, you should get results similar to these: 6-second rounding 66,240 (approx.) billing units, and 1-minute rounding 10,000 (exact) billing units. Furthermore, suppose calls are uniformly priced at $0.10 per minute (thats $0.01 per 6-second interval). Clearly, 1-minute rounding will result in a total bill of $1,000. However, by contrast, 6-second rounding will bring the total bill down to about $660. That's a big difference. Remember, the per-minute call rate is the same in both cases; rounding alone accounts for the difference.

When calls are rounded not to the next second, but up to some other time interval, for some fraction of your calls that fall short of the next full time increment, you are effectively paying for call time that you don't use. To see the significance of this effect, let's again look at some results from making 10,000 random calls based on a minimum and maximum time limit for the calls (see Table 2-19).

Table 2-19. Call-rounding effect: call time paid for but unused (approx.)

Call time not less than (seconds)	Call time not more than (minutes)	6-second rounding	60-second rounding
15	1	6%	38%
15	3	2.5%	22%
15	10	1%	9%
15	15	0.5%	6%
15	30	0.3%	3%

Even though SkypeOut rates are some of the lowest there are, the downside is that Skype rounds calls to the nearest minute. So, a call between 5 seconds (not 1 second, for reasons discussed shortly) and 60 seconds will be rounded up to 1 whole minute for billing purposes. Likewise, a call of N minutes plus 1 to 60 seconds will be rounded up to N + 1 minutes and billed accordingly.

2.12.1. Round Calls and Save Money

SkypeOut calls of 4 seconds or less are free (the clock starts running once you are connected). So, one way to save money is not to hang around if your call recipient's answer machine kicks in. Skype displays call duration in real time, so a careful watch and bailout before the first 4 seconds are up will save you a whole minute's worth of billing. Of course, if you do need to leave a message, you must sacrifice at least 1 minute of SkypeOut credit. But keep the message short, and you'll do yourselfand no doubt the recipienta favor.

Pay special attention to the fact that only the first 4 seconds of a call are free. Once a call is 5 seconds or longer you will be billed for a full minute. Thereafter, all fractions of a minutefrom 1 second to 60 secondsare rounded to a whole minute for billing purposes. So, for example, a call lasting 6 minutes, 1 second will be billed as a 7-minute call.

Skype's Terms of Service agreement, which you can find at http://www.skype.com/company/legal/terms/tos_voip.html, spells out all of this.

What the 4-second rule effectively allows you to do is round down the first minute to zero for calls lasting 4 seconds or less. This will be the only time you have the opportunity to round down, so make the most of it.

At 5 seconds and thereafter, when the minute mark rolls over into the next, a bite is taken out of your SkypeOut credit every time; therefore, you may want to force calls to be prematurely rounded. Whether your call is short or long, keep a close eye on the call timer. When the next minute mark is approaching, consider bringing the call to a close before you roll into the next minute. Ka-ching! Another minute's worth of credit saved.

A minute saved here and a minute saved there, and pretty soon you're into some serious savings. Just remember, the systematic application of these rules for call rounding will save you plenty in the long run.

For those readers who would like to analyze the economic effects of call rounding in more detail, perhaps in comparison with an existing call plan, a Skype Call Minutes Rounding Estimator spreadsheet is available from the book's web site at http://www.oreilly.com/catalog/SkypeHacks/index.html.