ZiPhone and Modem Firmware 04.03.13_G

I thought when using ZiPhone that it would downgrade the modem firmware to 04.02.13_G, yet it isn't. I am setting ZiPhone to jailbreak and unlock. The reason why I want to downgrade this is to be able to downgrade to 1.1.2 on one of my phones. I got it to do this before but suddenly the modem firmware won't downgrade. Any ideas? Thanks