Hello, after a few hours I got it working, this is how I make it works:
We need to configure the kernel of our gentoo b0x, we give support to ip and ppp
Networking --->
Networking options --->
<*> Unix domain sockets[*] TCP/IP networking
Device Drivers --->
Network device support --->[*] Network device support
<*> PPP (point-to-point protocol) support
<*> PPP support for async serial ports
<*> PPP support for sync tty ports
<*> PPP Deflate compression
<*> PPP BSD-Compress compression
then we make active:
Device Drivers --->
SCSI device support --->
<*> SCSI CDROM support
USB support --->
<*> Support for Host-side USB
<*> UHCI HCD (most Intel and VIA) support
<*> USB Mass Storage support
USB Serial Converter support --->
<*> USB Serial Converter support
<*> USB driver for GSM and CDMA modems
finally we compile our kernel and reboot the system, and then we add our modem with our Network Manager (gnome) and it will work fine
By the way, after reboot, as root : eject /dev/sr0 (to make it work)
Regards