Hi Arnoldnt,
Main difference between MD and BP is capacity. BP can have maximum 200 extensions, in a hotel version you can put 288 extensions, because room-to-room traffic is very low.
Trunks: officially 60 trunks are maximum, but I have a 90+ trunk system working OK, the only limitation is max 60 trunk calls that are possible in the same time.
Generally, BP is a feature rich system. A lot of very good features are implemented, for example voice announcements and messages, voice mail, are really good. IP trunking is allready implemented (I do maintenance of 6 networked BP250 exchanges, networking is done using IP trunking.
Digital telephones for BP250 are the same as MD110. BP250 has nice feature that one key can have two functions (like "shift" on a computer keyboard).
Speaking about hardware, BP250 has only one system board (CPU-D4) which covers the tasks of LPU/LSU/DSU/TMU/NIU/HDU.
DC/DC converters are integrated into backplane. There are two types of analog boards (8 and 16 extensions) and 3 types of digital (8,16,and 32 extensions). Furthermore, there is multi-functional board MFU which has 8 digital extensions, 4 analog extensions, 4 Basic ISDN (T or S -you choose by strapping )and some small voice mail. Also there are boards for analog trunks, Basic ISDN, Primary ISDN, 2Mb/s CAS MFC, 4W E&M, DECT, IP trunking & IP extensions, voice mail, etc..
Friend of mine says that difference between BP and MD is like this: BP250 is a small sport car, which has a lot of features, built-in stereo,air conditioner, etc..but you cannot put a lot of passengers into it. On the other side MD is a like a bus where you can put a lot of passengers, but you do not have so good comfort....
Best regards
Radoje