Difficulties to establish a ppp connection to a GSM provider

Question

I want to establish a ppp link to a GSM provider with my cell phone modem. The modem gets recognized and I can send AT commands just fine, but I can not get the connection established.

My chat script looks like:

#######################################
SAY 'Setting the abort string\n'
SAY '\n'
# Abort String ------------------------------
ABORT 'NO DIAL TONE' ABORT 'NO ANSWER' ABORT 'NO CARRIER' ABORT DELAYED

#######################################
SAY 'Initializing modem\n'
# Modem Initialization
'' AT
OK ATZ

#######################################
SAY '\n'
SAY     'Setting APN\n'
# Access Point Name (APN)
# Incorrect APN or CGDCONT can often cause errors in connection.
# Below are a bunch of different popular APNs

#REG:\s1 AT+cgdcont=1,"IP","proxy"
#OK     'AT+CGDCONT=0,"IP","proxy"'
#OK     'AT+CGDCONT=1,"IP","proxy"'
#OK     'AT+CGDCONT=2,"IP","proxy"'
OK     'AT+CGDCONT=1,"IP","m2mstatic.apn"'
#OK     'AT+CGDCONT=1,"IP","ISP.TELUS.COM"'
#OK     'AT+CGDCONT=1,"IP","INTERNET.COM"'
#OK     'AT+CGDCONT=1,"IP","ISP.CINGULAR"'
#OK     'AT+CGDCONT=2,"IP","ISP.CINGULAR"'
   ""

And in /var/log/messages I get the following messages:

Jan 11 04:08:49 ariag25 pppd[2518]: pppd 2.4.5 started by root, uid 0
Jan 11 04:08:50 ariag25 chat[2520]: abort on (NO DIAL TONE)
Jan 11 04:08:50 ariag25 chat[2520]: abort on (NO ANSWER)
Jan 11 04:08:50 ariag25 chat[2520]: abort on (NO CARRIER)
Jan 11 04:08:50 ariag25 chat[2520]: abort on (DELAYED)
Jan 11 04:08:50 ariag25 chat[2520]: send (AT^M)
Jan 11 04:08:50 ariag25 chat[2520]: expect (OK)
Jan 11 04:08:50 ariag25 chat[2520]: AT^M^M
Jan 11 04:08:50 ariag25 chat[2520]: OK
Jan 11 04:08:50 ariag25 chat[2520]:  -- got it
Jan 11 04:08:50 ariag25 chat[2520]: send (ATZ^M)
Jan 11 04:08:51 ariag25 chat[2520]: expect (OK)
Jan 11 04:08:51 ariag25 chat[2520]: ^M
Jan 11 04:08:51 ariag25 chat[2520]: ATZ^M^M
Jan 11 04:08:51 ariag25 chat[2520]: OK
Jan 11 04:08:51 ariag25 chat[2520]:  -- got it
Jan 11 04:08:51 ariag25 chat[2520]: send (AT+CGDCONT=1,"IP","m2mstatic.apn"^M)
Jan 11 04:08:51 ariag25 chat[2520]: expect (OK)
Jan 11 04:08:51 ariag25 chat[2520]: ^M
Jan 11 04:08:51 ariag25 chat[2520]: AT+CGDCONT=1,"IP","m2mstatic.apn"^M^M
Jan 11 04:08:51 ariag25 chat[2520]: OK
Jan 11 04:08:51 ariag25 chat[2520]:  -- got it
Jan 11 04:08:51 ariag25 chat[2520]: send (ATDT*99#^M)
Jan 11 04:08:51 ariag25 chat[2520]: expect (CONNECT)
Jan 11 04:08:51 ariag25 chat[2520]: ^M
Jan 11 04:08:51 ariag25 chat[2520]: ATDT*99#^M^M
Jan 11 04:08:51 ariag25 chat[2520]: CONNECT
Jan 11 04:08:51 ariag25 chat[2520]:  -- got it
Jan 11 04:08:51 ariag25 chat[2520]: send (^M)
Jan 11 04:08:51 ariag25 pppd[2518]: Serial connection established.

Edit

I don't think things are wrong with my chat script but my modem instead. Notice that on the bottom of the messages, the context switched from chat to pppd - why is that? May my power supply be too weak? That's what I suspect now. Any ideas?

Also, if I do a killall pppd after this and try to connect with screen

screen /dev/modem 9600

the modem doesn't reply anymore until I power cycle it.

However, I'm surprised! I hooked it up to a 2.1A USB power supply.

Edit2

My /etc/ppp/options looks like:

debug
/dev/ttyUSB1
9600
modem
crtscts
lock
connect /etc/ppp/net-connect
asyncmap 0
defaultroute

and /etc/ppp/peers/provider like this:

connect "/usr/sbin/chat -v -f /etc/chatscripts/pap -T *99***1#"

# Serial device to which the modem is connected.
/dev/modem

# Speed of the serial line.
9600

# Assumes that your IP address is allocated dynamically by the ISP.
noipdefault
# Try to get the name server addresses from the ISP.
usepeerdns
# Use this connection as the default route.
defaultroute

# Makes pppd "dial again" when the connection is lost.
persist

# Do not ask the remote to authenticate.
noauth

Solution 1

Drop the "defaultroute" line and it should work.

You can set the route manually if you have to, but you probably don't have to. It looks like you have a script hooked already that sets he routes when a new interface comes up and it's clobbering pppd.

Solution 2

Something is misconfigured with your pppd setup. If things are working correctly you should see messages from pppd in your logs similar to this:

Oct  5 12:37:35 localhost pppd[1289]: Serial connection established.
Oct  5 12:37:35 localhost pppd[1289]: Using interface ppp0
Oct  5 12:37:35 localhost pppd[1289]: Connect: ppp0 <--> /dev/ttyS1
Oct  5 12:37:36 localhost pppd[1289]: Remote message: Welcome!
Oct  5 12:37:36 localhost pppd[1289]: PAP authentication succeeded
Oct  5 12:37:40 localhost pppd[1289]: local  IP address 109.112.53.134
Oct  5 12:37:40 localhost pppd[1289]: remote IP address 109.112.235.129
Oct  5 12:37:40 localhost pppd[1289]: primary   DNS address 83.224.66.134
Oct  5 12:37:40 localhost pppd[1289]: secondary DNS address 83.224.65.134

References

• PPP over GPRS link how to
• A 10-Minute Guide for Using PPP to Connect Linux to the Internet
• 3G and GPRS modems with pppd

Comments

[Admin]

Stuck with the same kind of problem. In my case, pppd doesn't establish the network interface. Try dhclient ppp0.

[Admin]

What is your pppd configuration?

[Admin]

I don't think that's an issue with pppd showing up in your logs. Rather chat has done its job and is handing off control to pppd to get an IP address. I'd look to your pppd setup. It's probably getting hung up, and needs to be configured so that it can get an IP and set up your network connection properly.

[Admin]

This guide might be of some help in working through your pppd issues: linuxjournal.com/article/2109

[Admin]

@yegorich please see my ppp config above under edit2

[stdcerr]

Well, I don't, see edit 2 for my ppp config above