Earlier quoted context omitted.
The older Blackberries relied on a centralized server for configuration and setup of both public and corporate settings. The devices _should_ be able to make calls and text (baseline SMS), but they might error out in various things (browser dead, contacts gone, even some menus dead or stalling) and if they are reset you might not be able to get texting back (since it _might_ not rely on the SIM card to set the SMS me…
To further this, BlackBerries relied on a special GPRS APN to get access to the internet. BlackBerry had VPNs and leased lines with major carriers and Blackberries would communicate via the APN to proxies located in BlackBerry data centers. All the network config was stored on the phone in "Service Books" and could be pushed out via carriers or BES Admins.
That is why I said it _should_ still work for base calls (and likely SMS), but nothing else, really.