One of the keynotes given at last week’s Mobile Marketing Forum was given by Adhish Kulkarni (Buongiorno) and Karim Khalifi of Vodafone Egypt, about the various marketing activities that Vodafone has been up to over there.

One of the products they talked about was the very clever “Please Call Me” service, which is available for advertisers to sponsor.

PCM grew out an engineering issue, but also as a result of some of the characteristics of the market. 96% of the 30 million mobiles are prepay, which means that in a relatively poor country, an awful lot of people will be out of credit at any particular time. One unofficial and popular hack to solve this, would be for the consumer to call someone they want to speak to, let it ring once and then hang up. The recipient would then see they had a missed call, put two and two together and call back.

The problem was that this caused a lot of network congestion and so PCM was born, where people can send a free sms saying “Please Call Me”. Not only is this a more efficient use of network resources, but it stimulates more paid-for call minutes. And space in the sms can be sold to marketers who’d like to be associated with this useful service.

So far, PCM generates 180 million sms per month, so it’s not insignicant, by any means.

It amazes me that this kind of service isn’t more widely available and hasn’t been extended to all operators in markets with high percentages of prepaid customers. But then, operator take up of that other ideas such as the ability to transfer credits to needy or broke pals, or the micro-topup idea pioneered in the Philippines never seems to get traction elsewhere either.

If there are any operators out there who can explain why, I’d be fascinated to know.

This post is sent via the free wifi service in British Airways Executive Lounge. I know T5 has received terrible press, but honestly, it’s rather good. Strolling though the retail concourse this morning, surrounded by electronic posters and general whizziness, it really was like stepping suddenly into the future.

I’m on my way to do a panel at Web 2.0 in San Francisco. Hope to see you there!