Hmm so even if you can ever buy a secure phone you trust, you need to put another, completely opaque, computer into it to make it function (on cell networks anyway.)
They have a private GSM network at the CCC conference in Hamburg every year. Sim cards go for 2 euros (or you bring the one from last year) and it allows you to call anyone anywhere for free (for the duration of the conference, and you need to get a signal from the conference building of course). No GPRS or anything like that though.
