People already use WhatsApp to send texts, pictures, video and short sound files. If you're on a data connection, all the things you send and receive as data are broken into packets.
The same can be done with a voice signal: that's how Skype works, and it is available on mobile phones as well as desktop computers.
Carriers, especially those that make lots of money from international calls, have every reason to be worried. Text messaging, or SMS, has been the most golden of geese. It generated global revenues of $104bn in 2013. But this represents a peak as WhatsApp and other messaging apps such as BlackBerry Messenger and Apple's iMessage began to take over. The research company Strategy Analytics forecasts that SMS revenues will keep dropping, probably by another 20% by 2017.
If that's what WhatsApp can do to texting, what might it do to voice calling, especially abroad? Skype had little impact there, even though it's much cheaper, because it wasn't easy to use on mobile. WhatsApp offers much more in that arena. Its momentum is unstoppable, and with Facebook able to promote its use, there's every reason to expect that Facebook's billion users might soon be hooked up .
Carriers will then be reduced to competing on quality and speed of data coverage. Once revenue from voice calls starts dwindling, they will be reduced to companies that maintain expensive networks and hand out Sim cards to order.
Such a notion would have been startling at the turn of the century, when phone operators paid £22.5bn in the UK for next-generation licences. A generation of a different kind is taking over now.
guardian.co.uk © Guardian News and Media Limited 2010
image: © Jan Persiel