Dear Filippo,
Good to hear from you.
What I did, naively unaware of the challenges, I guess:
I installed usb_modemswitch, usb_modemswitch-data and vwdial via yum, assuming that these two packages are most likely to be required by most, though not all compatible USB modems.
I then had that old Huawei e172 modem flying around, stuck it in and had a go at wvdial.conf:
[Dialer Defaults]
Init1 = ATZ
Init2 = ATQ0 V1 E1 S0=0 &C1 &D2
Init3 = AT+CGDCONT=1,“IP”,"[YOUR_APN]"
stupid mode = 1
Modem Type = USB Modem
Baud = 460800
New PPPD = yes
Modem = /dev/ttyUSB0
ISDN = 0
Phone = *99#
Carrier Check = no
Password = airtel
Username = airtel
FlowControl=Hardware(CRTSCTS)
(unashamedly copied with a minor adaptation of the APN from https://sachinsharm.wordpress.com/2013/08/11/installing-and-configuring-usb-3g-datacard-on-centosrhel-6-3/).
Note: The APN is commonly “internet” (without the quotes).
There is a useful list of Raspberry-compatible modems: https://elinux.org/RPi_VerifiedPeripherals, which may well extend to Linux in general. Though concentrating mainly on 3g modems, there are a couple of 4g modems, too. AliExpress is a useful and very affordable source of those modems, because they are all Huaweis and ZTEs, made in China, nowadays anyway.
I have ordered in a modern 4g Huawei e3372 a few days back and expect to get it into Malawi in, well, two months’ time. Despite the delay, it will be very useful to paly with, next to my old, yet still rock-solid Huawei e172. You will note that those “old” models are still going strong all over those countries that jumped the landline queue, and do everythying mobile.
An important alternative to USB modems, and probably huge;ly more accessible from Europe, too, is the option to tether your SmartPhone via USB (or Wireless) to the NethServer. USB tethering is easy to set up. In Debian speak, it would be something like:
auth usb0
allow-hotplug usb0
iface usb inet dhcp
and you are done.
Both option could be rather interesting to those without a landline, DSL or external router. Given NethServer’s powerful firewall, this setup would not pose any additional security risk, but may rather increase security buy leaving all management in one hand/device.
Though I have zero spare time at present, I can certainly help with the hardware, networking and testing side. I might be less fluent in producing the right user interface in NethServber :-/.
Let me know your thoughts and have a great day,
Chris