UMTS connection fails with "LCP terminated by peer"

Question

I use the Ericsson N5321 gw card in my Lenovo Thinkpad T440s to connect to T-Mobile (resold by debitel) with the following /etc/wvdial.conf (on debian sid x64):

[Dialer Defaults]
Modem = /dev/ttyACM2
Baud = 460800

Phone = *99#
Username = t-mobile
Password = tm
Stupid Mode = 1

Modem Type = USB Modem
New PPD = yes

Dial Command = ATDT
Init1 = ATZ
Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
Init3 = AT+CGDCONT=1,"IP","internet.t-mobile"

However, when I try to connect, ppd fails with code 16 and log:

Aug  3 09:47:01 t4 pppd[3592]: CHAP authentication succeeded:
Congratulations!
Aug  3 09:47:01 t4 pppd[3592]: CHAP authentication succeeded
Aug  3 09:47:01 t4 pppd[3592]: LCP terminated by peer
Aug  3 09:47:01 t4 pppd[3592]: Modem hangup

How do I make the connection work?

Answer 1

To actually use the modem for an Internet connection, you need to activate it with the AT+CFUN command. Modify wvdial.conf to send AT+CFUN=1:

[Dialer Defaults]
Modem = /dev/ttyACM2
Baud = 460800
ISDN = 0

Phone = *99#
Username = t-mobile
Password = tm
Stupid Mode = 1

Modem Type = USB Modem
New PPD = yes

Dial Command = ATDT
Init1 = ATZ
Init2 = AT+CFUN=1
Init3 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
Init4 = AT+CGDCONT=1,"IP","internet.t-mobile"