I have FOP2 2.26 installed, and I have entered some data in the phonebook. Fop2 correctly shows (in the notification box that pops up when my phone rings) names for external callers when number is matched in the phonebook, but when an extension (number 34) calls me, the phonebook matches the number (34) to the last two digits of a phone book contact that has a number that ends in 34 (05164455334), and shows me the external contact name, which is clearly wrong.
I think that the number matching should be done using at least 5 or 6 numbers, so that estension numbers do not match phonebook records that end in the same 2 numbers as the extension.
Ideally the minimum lenght of a number to be matched should be configurable, with a sane default of 5 or 6 numbers.