July 6, 2004

When You Shouldn't Use Voice Over IP (VOIP)

There's been a lot of talk recently about Voice Over IP and how it wonderful it is.  In many regards it is kinda cool.

But there are situations in which people ought to be careful and should carefully consider whether VOIP might work to their disadvantage.

The reason is simple - delay.

A typical POTS (plain old telephone service) phone has nearly no delay - the receiver hears at about the same time you speak.  If there is a delay it is often only a few milliseconds, a time that is barely noticeable to people.

VOIP phones, on the other hand, typically insert a few hundred milliseconds (1000 milliseconds = one second) of delay.  This delay is present even if the two phones are on the same LAN.

An easy test is to find some phones where the two parties can see one another.  Have one person tap the mouthpiece with a pencil.  You can then clearly see the time delay (or near-absence of delay) by observing the time between when you see the pencil tap the phone and when you hear the tap.

The extra mouth-to-ear delay of VOIP can be bad because that extra delay can make people sound impaired, drunk, or just plain stupid.  Our perception of the intelligence or capacity of the other party is strongly shaped by the speed with which the other person responds.  With VOIP, no matter how fast the other person thinks and answers, there will be a noticeable delay.

So, if you are a person who's business is based on a perception of intelligence or expertise - for example, if you are a doctor or lawyer - then you may want to consider sticking with analog telephones.

And if you are a person who has to deal carefully with delicate situations - for example if you are handling a suicide line - then you might also consider avoiding VOIP.

And finally, if you engaged in telephone based auctions then you might want to consider whether the quarter of a second of delay typical of VOIP will create a bidding disadvantage.

Posted by karl at July 6, 2004 10:57 PM