Hi I guess that it is really a moot point since you have already left SO, but I'm curious about your being charged long distance for picking up Voice Mail (VM).
That is totally contrary to my experience. If you can shop at London Drugs you are in or west of Winnipeg as there is one store in Winnipeg and 3 in Saskatchewan, and the bulk of the stores are in Alberta or BC so your experience should be similar to mine.
If you are using a SO phone when you activate your voice mail, my experience is that the system recognizes the SO phone and sets it to the appropriate VM number when you press and hold the 1 key for the first time. If you were using a non-SO phone like a Rogers phone or an unlocked phone from Fido or some other carrier, there is no promise that phone will dial the number for VM as toll free unless you set it up. Pressing and holding the 1 key on a Rogers phone will dial the Rogers VM that was programmed into the phone. Same if the phone was a Fido phone. You may get your SO VM there as SO and Fido use the Rogers VM servers — but with distinctive call in numbers. If you used a non-SO phone to set up and/or access the VM system, you would have needed to do some configuration.
SO don't charge for calling within the same area code as the phone. You can get voice mail by dialing your own SO phone number from your SO phone (call yourself) and pressing the # key when the system answers the phone. It is impossible for that call to be long distance. It is from your Area Code XXX phone to the same phone. You can call any phone including your own in your home area code as a local call no matter where in Canada you actually are when you make the call. As I said, it is impossible to turn that call into a long distance call.
If you set up your VM using a SO phone and then switched the SIM to a non-SO phone, you would have to change the speed dial on the non-SO phone for the 1 key to the correct SO pickup number for your area code — It will not do this automatically. SO Customer Service likely won't be much help here — after all they can't support phones they have nothing to do with.
If you did transfer the SIM to another phone FAQ 15a on this site lists several numbers for SO Voice Mail retrieval. There are others for other areas of Canada in this thread.
I have direct personal experience using both Area Code 250 and Area Code 204 phones where the SO VM servers are in different area codes than the phone. I have set up non-SO phones to access VM in both those area codes and verified by checking balances before and after calls that my call was charged as local. I can sit in my home in Victoria BC and call the pickup number for my SO voice mail for a Manitoba number and it is charges as a local call. I am physically in an area served by area code 250, using a SO phone with a 204 area code, calling a 403 number, and it is charged as a local call. I've proven that more than once by checking my account balance before and after picking up voice mail.
As far as the market SO cater to, this forum and 7-11 Speakout's own page make no bones about the fact that SO is best for intermittent and/or light cell phone users. There is no other service that gives 365 day top ups for $25.00. That only gives you 44 minutes after the 911 fee is paid but it gives you a year to use that time. There is a breaking point at which you are better buying a plan from another carrier — just remember to either tie the payment to a credit card a regular bill, and/or be prepared to buy monthly top ups.