The /etc/wvdial.conf for my free sim card.

To allow a standard user, it must be part of the dialout and dip group.

[Dialer Free]
Modem = /dev/modem_huawei_00
Init2 = ATZ
Init3 = ATQ0 V1 E1 S0=0 &C1 &D2
Init4 = AT+CGDCONT=1,"IP","free"
Stupid mode = 1
Phone = *99#
New PPPD = yes
Check Def Route = 1
Username = free
Password = free
Baud = 3600000

Ensuite, pour activer la liaison:

wvdial free