IP telephony explored

A group of talks considered the issues that can arise when IP telephony is connected to the conventional telephone network and, in particular, those resulting from the very different charging models used by the two technologies. Internet users and providers are now used to flat-rate, unmetered charges, where monthly bills are constant and predictable whether or not the connection is used. In contrast, conventional telephony still uses per-call or per-minute charging: in the case of premium-rate numbers a ten-minute phone call (or ten one-second calls) may cost as much as a month's internet access.

Within a day, therefore, a user of an IP to phone gateway can easily incur a telephony bill that they are unwilling or unable to pay, potentially leaving the gateway operator with an unrecoverable financial loss. Gateways that wish to protect their users and operators therefore need to be sure who their users are, monitor in near real-time the costs they incur and, if necessary, impose limits based on individual users' preferences and ability to pay.

Andrew Cormack at the FIRST 2009 conference
(http://conference.first.org/)