Some telephone points to be connected in an office

I have a new phone connection in my office. It is in one room, but I sit with my colleague in the room next door, so I would like to be able to plug a second phone in there and also be able to connect my computer to the internet with an ethernet cable. So I would like three extra phone points connecting (all on the same line). The office already has sockets built in under little hatches on the floor, which I would like to use.