Hi,
My friend seems to have the same problem. I am using a Blackberry Curve 8900 on the O2 network and he’s got an Blackberry 8100 on ‘Orange’. It works on mine.
If you are getting messages with +44 and an English number, your Argentinian friend must’ve sent you a text first (?). You should be able to simply click ‘reply’ as this works for me. However, what is odd is that if I text this friend in particular by using her own mobile number, her reply appears with an English number. Must be something to do with who texts first.
Re: delivery reports. I had a tick next to one of my texts and I know for a fact it didn’t get to Argentina. I rang O2 and they said that the tick only means it’s gone as far as the English network, not Argentinian one.
Jez