Подключил модем к USB.
# lsusb
Bus 001 Device 004: ID 1076:8000 GCT Semiconductor, Inc.
#dmesg
usb 1-4: new high speed USB device using ehci_hcd and address 4
usb 1-4: configuration #1 chosen from 1 choice
cdc_acm 1-4:1.2: ttyACM0: USB ACM device
usbcore: registered new driver cdc_acm
drivers/usb/class/cdc-acm.c: v0.25:USB Abstract Control Model driver for USB modems and ISDN adapters
eth2: register 'cdc_ether' at usb-0000:00:1a.7-4, CDC Ethernet Device, 0c:00:0e:00:c0:0d
usbcore: registered new driver cdc_ether
# ls -la /dev/ttyACM0
crw-rw---- 1 root uucp 166, 0 Jun 7 11:40 /dev/ttyACM0
PS.
Собственно раньше к другим модемам цеплялся minicom ом. Этот не реагирует.