RJ11 is the standard telephone port for POTS (Plain Ordinary Telephone Service) system. In Allegheny County, Verizon owns the POTS network. They do not wish to keep this network running, but I am guessing there is something legal requiring them to support their current customers. However, moving customers, and new customers will not be supported. If you insist on Verizon to be your landline telephone provider, you will need to find another residence that would support FiOS telephone services. There will be no telephone cabling ran in the building.
You have a couple of options if you want a home phone service. The first is to acquire a cellular ATA (Analog Telephone Adapter). A number of cellular companies offer such an ATA for service. However, in my opinion, this will be rather silly, and it will just make more sense to have a cellular phone then. The second option will be to use VOIP (Voice Over Internet Protocol). You would use an ATA that is either unlocked (and you have to provide the credentials), or through a closed provider such as Ooma, or Vonage for Home. You plug your phone into the ATA, and then you plug the ATA into an ethernet jack.
Since internet will be included, the VOIP option will be a good option. This is again assuming that you need a home telephone number. I have a home telephone line using a Wifi Phone instead of the ATA, and it is by choice. I could just as easily rely exclusively on my cellular phone for telephone calls. If you decide you want a home telephone, and want everyone to be able to use the same line, I will recommend a DECT (Digital Enhanced Cordless Technology) base station with 4 phones. One could be in the great room, office, and each of the bedrooms. You would plug the base station into the ATA.