Please tell me how it work. I have 1.1.3 (OTB 1.1.1) with firmware version 04.02.13_G. When I used Ziphone the firmware version is the same.

Today I did the same to my friend's 1.1.1 IPhone and I noticed the modem firmware version is newer then mine but it was older before upgrade! Why is that? Is it Ziphone that upgrades it? If so how can it decide it? What good things can I have with newer firmware than mine?