Text Shortcode Providers?

[SCEtoAUX]

Hello all.

A driving school client has asked me to investigate the use of text shortcodes. (Text "call me" to 12345 for example).

Does anyone have any experience using these and equally can anyone recommend a provider?

Thanks very much.

[DoubleByte]

Many moons ago I did some work with reverse billing short codes but the SMS gateway company appears to have disappeared.
All I remember was it was expensive unless you are prepared to share a short code.