What is a mobile phone cap or cap plan?

This is an extract from a Melbourne Age article Rather than pay for each call and SMS the usual way, these plans mean users only pay a certain amount per month (the "cap") if their usage doesn't...

Dear sexy girls or boys it is plain

the difference is that if you are on lets say a $49 CAP. it means that you will only pay $49 and you will get all the free calls and texts included. but if you are on a $49 PLAN that $49 is for...

To turn on caps-lock, double-tap the shift button (up arrow). To turn caps-lock off, just tap the shift button once.

a cap plan on a mobile is a certain amount of money you pay every week/ or month for 1-3 years until you have finished paying it off.