Hello again,
Another question: in your book, page 12, I read:
"If handheld is roaming to a foreign cellular carrier....the data from the handheld unit will travel to the roaming carrier's data backbone network, then to the home carrier's backbone network, and finally to the BlackBerry NOC"

I was under the impression that handheld traffic was hiting the visited carrier BlackBerry NOC Connection first, and not roaming to home backbone network via GRX - because:
-> flat BlackBerry International roaming charge would stand for this model rather than GPRS roaming to home carrier and expensive GRX costs
-> apparently some users have reported that in some countries, GPRS is supported (with roaming agreement with home network) but not BlackBerry service..

Thanks for your answer