[andy]

IoM mobile is counted as UK mobile by most providers, including such UK ones as call18185 and various 0844 callthrough numbers. Where there are different tariffs for the various UK mobile networks, then it is either counted as O2, has its own tariff, or is occasionally not defined and unobtainable (from a couple of US firms).

For callback to the IoM number I use Voipfone, either with a wap version of their call-me-back button (after diverting my incoming Voipfone number to the SIM), or by diverting my O2 phone to the IoM number and then using either sms or the callback trigger number - texts are included in the O2 contract even when roaming (used at 4 for 1), and the IoM SIM has no caller ID at present.

I also use CBW with the Liechtenstein SIM, and Enlinea with some single country ones, though more recently have found both Voipfone and Mywebcalls have cheaper rates for several countries