visual voicemail on other networks

Hi Everyone, does anyone know of other networks who do visual voicemail... apparently the technology of the thing is quite "old" but Apple seem to have managed to limit it to the 2 networks... how?

I find it hard to believe that they would only give this "secret" to its 2 networks, only because it gives those networks a bargaining chip, something Apple has kept away from it's networks as it seems to be getting a lot from these guys but giving very little indeed (aside from the exclusivity of the God Phone except they know full well people can unlock it if they wish!)

Indeed, if T-Mobile win the Germany bid, which seems likely will T-Mobile users get access to the voicemail feature?

So any ideas on this guys, will we see visual voicemail on unlocked iPhones.... God I hope so!!!!

 

but how do they keep it exclusive if the technology is well known?