Hello andrazh,
you can not take any intercom. You must look what intercom system is installed in your house. To find it out, you can ask your neighbour or the owner of the house. Then you can buy it.
To connect the new one, look for your neighbour. The connection terminals there and frrom you must have the same color.
The doorbell can use DC or AC and sometimes only a sound produce be a generator. Here you must know how it is in the other apartments. Check this out before you try something, because you can disturb all other doorbells in the house.
When you find out what system is installed, ask again if you have problems
Regards
Rainer