@rae820-
In short, the last 2 "octets" are likely changing because you are dealing with a Class B network of some sort. The first 2 octets are probably assigned to that provider's network (Blackberry Network) and the last to relate to the Host or Node from which the connection is coming from (ex: device which is connecting and/or using that network for an internet connection).
more detailed definition of an IP address schema:
http://computer.howstuffworks.com/question549.htmUnfortunately, unless that network assigned some sort of static IP to your device, it will likely change frequently and simply pick up the next available node address when it connects (last set of octets). It works the same as if you had your own network setup at home and allowed each PC in your house to "obtain automatically" the IP address/node address from the DNS server (likely your home router in that case).
Swytch~~
