It looks like Geodesa is charging 13p incoming, but Simazing appears to still be free there
http://www.globalsimcard.co.uk/coverage.htm
http://www.simazing.com/coverage.htm
09 Mobile also has free incoming calls there, and people on here have used it with Enlinea for 10c a minute outgoing
Even a Vodafone UK payt SIM with Passport looks useful for longer outgoing calls - off-peak calls (local time) are 5 pence a minute to UK and NZ landlines, and you could go via a UK calling card or 18185 for other destinations. If you can plan to make a series of consecutive calls, pressing # to follow on calls with the calling card but stay connected with Vodafone cuts down on 75p connect fees. If you do, I'd suggest using an IoM SIM for incoming calls and don't give out the Voda number