I am in the proscess of writting an c++ application to menage a modem connection on my arm board. I would like to use the wvdial utility for this. Unfortunately I have a problem. When startng "wvdialconf" the modem is detected and the file "wvdial.conf" is initialized.

# sudo wvdialconf
Editing `/etc/wvdial.conf'.

Scanning your serial ports for a modem.

Modem Port Scan<*1>: S0 S1 S2 S3
ttyUSB0<*1>: ATQ0 V1 E1 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 Z -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 -- OK
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK
ttyUSB0<*1>: Modem Identifier: ATI -- 332
ttyUSB0<*1>: Speed 4800: AT -- OK
ttyUSB0<*1>: Speed 9600: AT -- OK
ttyUSB0<*1>: Speed 19200: AT -- OK
ttyUSB0<*1>: Speed 38400: AT -- OK
ttyUSB0<*1>: Speed 57600: AT -- OK
ttyUSB0<*1>: Speed 115200: AT -- OK
ttyUSB0<*1>: Speed 230400: AT -- OK
ttyUSB0<*1>: Speed 460800: AT -- Speed 460800: AT -- Speed 460800: AT -- Max
speed is 230400; that should be safe.
ttyUSB0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK

Found a modem on /dev/ttyUSB0.
Modem configuration written to /etc/wvdial.conf.
ttyUSB0<Info>: Speed 230400; init "ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0"

My "wvdial.conf" file:

[Dialer Defaults]
Init1 = ATZ
Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
Init3 = AT+CGDCONT=1,"IP","myapn"
Stupid Mode = 1
Modem Type = Analog Modem
ISDN = 0
New PPPD = yes
Phone = *99#
Modem = /dev/ttyUSB0
Username = " "
Password = " "
Baud = 230400

But when I try run "wvdial" or "wvdial -c" or "wvdial

# sudo wvdial
--> WvDial: Internet dialer version 1.61
--> Warning: section [Dialer Defaults] does not exist in wvdial.conf.
--> Cannot open /dev/modem: No such file or directory
--> Cannot open /dev/modem: No such file or directory
--> Cannot open /dev/modem: No such file or directory
# sudo wvdial -c
--> WvDial: Internet dialer version 1.61
--> Warning: section [Dialer Defaults] does not exist in wvdial.conf.
--> Initializing modem.
--> Sending: ATZ
--> Sending: ATQ0
--> Re-Sending: ATZ
--> Modem not responding.
# sudo wvdial /etc/wvdial.conf
--> WvDial: Internet dialer version 1.61
--> Warning: section [Dialer /etc/wvdial.conf] does not exist in wvdial.conf.
--> Cannot open /dev/modem: No such file or directory
--> Cannot open /dev/modem: No such file or directory
--> Cannot open /dev/modem: No such file or directory

Unfortunately I have no idea to. The configuration file exists but wvdial does not see it. I don't know if it matters but I don't have file "pap-secrets" and "chap-secrets" in the path "/etc/ppp/"

haha. good stuff. I was working on few things like that in the past. see my posts (or others). But forgot mostly the topic.
However, I can share few thoughts with you
example (using pppd instead of wvdial) https://www.linuxquestions.org/quest...ta-4175463323/
https://www.linuxquestions.org/quest...hy-4175474013/
etc.
keep calm. no hurry.
(my impression: you dont call correctly your /etc/wvdial.conf )

You need to put your ISPs information in the red fields. Have a look at this guide.

When I wanted to enable wvdial with correctly loaded configuration I got:

This is not a missing number, password and phone number problem because wvdial stops working early and doesn't even send "init". I have the same configuration for raspberry and it works.

Please revise your post (I dont understand what you want).
1. Post YOUR wvdial.conf
here is one of me
2. Post how you initialized the modem and called the provider with your conf file with wvdial "wvdial -c Fonic" or other
3. post all messages after you made 2)
(or look at several successfull wvdial use anywhere else)