mod my VS7 to work on 850 Mhz band? Help please!

I'm trying to modd my Panasonic VS7 to work on 850 Mhz band.
When I use Phone Tools v9.5 and it show this on the status windows when I conect my VS7:

Target SW Ver: NBG_LEOPARD_05.24 SMARTI_SDB1 SGOLDliteV1.1
Target EEP Ver: 150
RF Band Support: 850 & 900 & 1800 & 1900Mhz
RF:
BaseBand: S-GOLDlite v1.1
Features present: FFS, BlueTooth, AM/FM Radio., MPEG3, Voice Rec, Reduced Signaling Test, Camera, LED & Backlight, IrDa, Monitor Sig.,

So, I guess there is some way to enable 850 band. I really need it because here in southamerica the carriers use 850/1800, so in non-urban zones I lost signal, and like I travel all the time this is very inconvenience for me.

If someone can help me (links, hows to, etc.) I will thank you a lot!!!

Anyone?

You could try renting a phone. A company in Southamerica I know: Altel.com.ar

Regards,
Senior