You will still need to provide Call Control from some device other than an 800 series router. Preferrebly, you will want to purchase, at a minimum, a 2811 Router with a Call Mgr Express bundle (as was stated above by surbabu140977). This will include the required licenses, PVDM, and purchased analog cards that you will need to utilize in order to provide dial tone to the other devices. Now, with an analog card in the 2811 router at the first house, you can provide dial tone to at least four phones via a four port FXS card. Now you have to address the other two houses and any future dwellings. So you can either provide the softphone application running on a desktop/laptop, or you can provide a physical phone. In the physical phone case you will need some device that will allow you to plug the phones into it, that device will also need to communicate back to the CME router at house number 1. Least expensive option is the softphone app. Be weary that most people are not used to using a software based phone. There is a USB phone option out there, but it is not Cisco.
