I'll be going off topic here, but I have to chime in since cell phones used to be my forum hobby before Tomtoms......
North America differs from most of the world in cell phone frequency. The US developed its cell network on 800 mhz, and Europe developed its network on 900 mhz. When "global roaming" started to be considered, and people wanted to harmonize the frequencies, they realized a major problem: the US sold tons of 900 mhz cordless phones and had no spectrum left for cellular on 900. And european militaries took most of the 800 mhz, so there was no spectrum left for 800.
Canada decided to launch 800 mhz cell due to proximity to the US. Most of Europe, Africa, and Asia launched 900 mhz, and Central/South America had both, depending on country.
A decade later when the 800/900 mhz spectrum filled up, governments looked for free unused spectrum and the whole scene repeated itself, North America added 1900mhz and Europe added 1800mhz.
So for a phone to work on all networks, it needed coverage on all 4 bands.
Now fast forward to 3G - and the same thing happenned. Again, due to scarcity of spectrum, there are now more bands to deal with, 1700 mhz and 2100mhz. And 3G requires a pair of bands due to its data load, and what's worse each carrier (even in one country) ended up operating on a different pair. A truely global 3G phone needs to be 6-band compatible.
Fast forward to 4G and a 7th band was added - many carriers are taking the 700mhz band that is being vacated by analog TV, requiring 7-band phones.
Separate from frequency is communication protocol. Europe, in the spirit of interoperability, mandated everyone more to GSM. America let competition drive its standard, resulting in 6 incompatible standards (CDMA, GSM, TDMA, IDEN, and AMPS). Japan had a few of its own, including a unique one for DOCOMO, the first 2G carrier in the world. Each protocal had its pros and cons, and is still around in some form or another, except for TDMA.
The good news is that most (all??) carriers worldwide have agreed to transition to LTE for 4G, a new protocol that blends the spectrum efficiency of CDMA and the SIM-portability of GSM. My suspicion is that the GO 950 will be an LTE device, permitting Vodafone HD traffic on Verizon's network.
Rogers is 800/1900 mhz GSM, and quad band phones will run calls and 2G data almost anywhere.
Telus is CDMA, and the 8830 is actually a dual band CDMA (800/1900) and a dual band GSM (900/1800), so it's actually a quad band phone and similarly will work almost anywhere.
