Bell has the option to see that information and I feel it helps with deciding plan selection and changes to extras(data). My roommate is with Bell and I find it informative.
Hi Darth. I wouldn't be over-awed by carrier tools. They lull you into believing you can pick a better plan when in reality there are 'gotchas' in every plan - no matter which plan you have you'll either pay too much for it or you'll blow over the limit and pay overage fees on a regular basis.
The best approach i've seen so far is to pick a reasonable pooled amount, i chose 2.5GB per phone, 10GB total, and I refuse to go over it no matter what. There is a simple-stupid internet app that helps me track.
If any phone gets out of line I shut off the phone's data until its sorted out - if i decide to sort it out. Either way, once its back in line I switch the data back on.