If the phone cradle (and various controller bits + cables that you can't see) are original, then the phone in a 2001 was a Motorola Timeport. Replacements from MB were tough to find in 2002 (Mot quit making them for MB), I'd bet they're darn near impossible to get from the dealer now.

Your options are likely limited to: 1) upgrade the cradle/controller/etc to whatever MB is using now (> $1k plus the cost of a new phone from MB (~$500)), or 2) buy a replacement phone off eBay.

A quick search on eBay finds at least one (here). No affiliation, not responsible if it is a ripoff, etc etc. But it might be worth a roll of the dice.....