Observations:
1. It doesn't work in Europe. European service providers aren't
supported; You can't even enter a UK-style phone-number in the
subscription form; and phoning an SMS service in the US would be a
tad pricey.

2. A European version is planned, supposedly for release in January.

3. In North America, the recipient of a text-message pays. In the UK
(and most of the rest of Europe, I believe) it's the sender who pays.

I've done a fair bit of work on mobile telephony (paid, day-job work), and I'd be interested in setting up a UK version. But it seems to me there's a big problem - if you allow free subscriptions, as TxTMob do, then one way or another you have to figure out how to pay for relaying each incoming message to potentially large numbers of mobile subscribers. Text messages cost 10p each to send; so a single message to a group with a hundred members would cost the operator a tenner.

Can anyone offer suggestions as to how a system of this kind could be financed in the UK environment?