I have the same issues sometimes when I log in to do my quarterly VAT return. Can't get anything done until my smartphone gets a signal so that I can collect the damn code. Fortunately for me, though, a walk around the garden is usually enough. I certainly can't send text messages if they've got photos attached.
There should be a network app available that links wifi/BB log in to your mobile only services like SMS and voice calls.
I use the 3 one called in touch for just that when I'm up in the hills with in building wifi but zero mobile signal (of any flavour).