When there are multiple phones on one account it would be great if the data on each phone could cross over if one phone uses more and one uses less. IE. if there are two phones on one account, each with a plan that allows 1gb of data per month which would equal 2gb of data per month between the two phones.. So if phone #1 uses 1.3Gb of data and phone #2 uses 600mb of data the total data is still under 2gb and therefore no additional charge. That OR if when phone #1 goes over it's mthly data and a 500mb add on is paid for, that add on can be shared between any phones on the account (phone #1&2 both have 1.2 gb of data only one 500mb data add on is applied).