I've just had same problem as Rob M
The software update to fix the sms security problem started well, then it stopped, and ever since it's been saying i need to restore as its stuck in recovery mode.
I say okay fine restore, an it does somthing with the phone for a few mins, an then comes up with the error 1604. and i can't restore it.
Have just been on a mad internet rush looking up 1604 an fixes, but its not working!
Any help??
(my 1st apple product, an yet this feels like something a microsoft product would do
)