Multiple lines question

Hi folks,

I'm in Toronto Canada, and for the last couple of years I've had a Bell
Mobility phone and plan. NowBell's nice and all but they're a little pricey
for my very light usage. As such I was thinking about going with either
Telus/Clearnet or Fido. And as it happens my new boss has decided I need a
company phone. So I was wondering, are there any GSM phones I can buy which
will allow two active lines? The one for my employer, and my private line -
thus requiring me to carry only one phone.

So I guess really the above is two questions: Are there any handsets which
allow multiple lines, and can I get multiple lines from multiple accounts on
the one phone?

Did that make sense? I hope so...

Thank you all!

~ Ian