Top row: modem lines.

Bottom: Ethernet.

We are also running Cat5 TP cabling to four other companies residing with us in the building.

We are actually reusing some of the modem lines for POTS telephones because we have eventually hit the ISDN-phone capacity limit of our PBX while almost none of our customers are still using modems anymore. (We are providing Internet services exclusively to the business market, and this means mostly digital leased-lines. ISDN is well deployed here in Germany.)

You don't want to have our PBX. It's a dinosaur of a PBX, more adaequate to be used in a setting such as a WalMart store where three of them get interconnected to serve 500 desk phones with intricate policies who may do what regarding telephony features. We could use it to implement an arcane mix of rotary modem pools and voice telephony to the desk.

But all in all, the beast is simply not cost effective. Implementing CTI solutions based on it is prohibitively expensive, and for data lines, we use dedicated access routers today.