Ryan,

This should clear up things....

As a general rule (DIY), wire phones in PARALELL not SERIALLY

All phones will have what is called a REN number. (Ringer Equivalence Number)

This relates to the power required to make a phone ring when you get a call.

An average BT line is able to supply a REN of 4 normally.

ALL phones should display a REN number on it somewhere BY LAW !

Add up all the numbers and if is greater than REN 4 then it is possible that randomly
one or more of the phones may NOT ring when an incoming call occurs.
Also, this draws more power from the exchange and can cause the line
protection to kick in and kill the line in extreme cases.