Why can't a certain person receive my text or calls?

I have recently moved from my mums house in with my wife in a different county.
were i'm currently living i have a bad 3G signal and my phone signal is a medium level, usally 3/5 bars.

i have a iphone 4s 16gb on tesco mobile ( which uses o2 signal )

my mother has a very basic phone which is only used for calls and text. ( t-mobile )

for some unknown reason to me we can't call each other and our text arn't going through to each others phones.
none of us have blocked each other numbers as we get on, on very good terms and love to keep in contact with each other.

Keyboard clicks, lock sounds, ringer etc.not working but iPod is? (iPhone 4s)?

I've had my iPhone for about 6 months and the buttons on the left hand side have stopped working, the keyboard clicks, lock sounds, ringer, alerts and app sounds don't work through the speaker but music will play through the speaker. All of my sound setting are turned on but still no sound? Vibrate works but sound would be pretty helpful.

Why does my iphone 4s always say multiple calls when i place a call on hold?

If i'm on a call and get another call come thru on my old iphone 3gs it would say hold for the top caller and i can either merge the calls and swap from one another but with my current iphone 4s i click hold call + answer and right away it says multiple calls and i can't swap from one call to another the only thing i can't tell is if it places the calls on a three way? And if i'm done with the second caller i can't swap back to the first caller withour hanging up and calling again? I have service with sprint would this have something to do with it? Would any one know what the issue is? Any help would be appreciated thanks!

Iphone 4s armband that fits over case?

I bought a normal iphone 4s protector case and was wondering if anyone knew of any armbands (so you can wear it one your arm while running, for example) which would fit around the case that's already on my phone - it's a tightly-fitting (although adds some bulk) case which would be a pain to keep putting on and taking off every time i wanted to use the arm band.

Making twitter account public?

So my laptops broke and I've forgot my twitter password but I'm signed in on my iPhone, is there anyway I can make my profile public from my iPhone?