Kyle,
Here's a Halloween inspired explanation.
Just think of it this way. The 'brains' of your phone is the SIM card. And just like some old Frankenstein horror movie, you can perform a brain transplant into whatever body (errr… phone….) that you want, provided that the body (phone) has an empty head to place the brain.
What kind of body (phone) is required for a brain transplant? Well, it has to be a GSM phone, since you can separate the brain and body with GSM phones, and you can't do that with CDMA (Bell and Telus) phones. (plus the technology is different, etc etc).
Then the new host body (phone) must be able to accept the new brain. Some bodies (phones) are locked to a certain type of brain (SIM cards from a specific company like Rogers or Fido), while other bodies can accept any type brain.
The brain's memories (phone number, balance on your plan, etc) are stored in the brain, not the body. So you can transplant the brain in a Motorola body, load it up with money, use it for a while, then transplant the brain into a Nokia body, and everything stays pretty much the same.
Your phone number, balance on your account, and maybe your contact list (see below) are all associated with the brain, not the body. You can have a different body for every day of the week, and as long as you're using the same brain, Speakout or PetroCan don't care.
Notes about Brain Transplants:
You'll have to remember to configure the new body so that it knows what the Speakout/PetroCan voicemail phone number is. So when you get a voicemail and the phone asks you if you want to listen to it, it knows where to call. You'll just have to do that once.
When you are typing in all your friend's phone numbers, try and make sure that they are stored on the SIM card (brain). Sometimes you will store them on the phone (body) so when you do a brain transplant the numbers will still be on the original body. If they are on the SIM card, you'll have them with you regardless of what phone you're using.
Disclaimer:
Big Ang is not a brain surgeon, nor does he play one on TV. Big Ang is not responsible for you creating a Frankenstein-type monster, who then might wreck havoc on the nearby town. Big Ang is not responsible for any death or damage to any property or persons if the townsfolk rise up against you and charge your castle with torches and pitchforks.