Netgate Discussion Forum
    • Categories
    • Recent
    • Tags
    • Popular
    • Users
    • Search
    • Register
    • Login

    3G/4G modem configuration (MC7700) problems with PPP and error: CHAT: Invalid d

    Scheduled Pinned Locked Moved Hardware
    3 Posts 2 Posters 2.2k Views
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • J
      jamest
      last edited by

      Hi all,

      I have built a custom image that has added support for the MC7700 Sierra Airprime internal 3G/4G modem.  I am using the Nanobsd build on an Alix router board.

      The devices are detected and I correctly see a number of /dev/cuaU0.0 - /dev/cuaU0.3 devices as expected.
      I am able to use the PPP command to query the modem and get some modem information out, so I am happy that the card is working.

      However I can't seem to get the modem to connect due to the error in the ppp log of pfsense:

      CHAT: Invalid dial init string.
      

      Unfortunately I don't really know much at all about 3g modems or PPP so struggling a bit with the required knowledge.  I have configured pfsense to use the device /dev/cuaU0.2 as the modem as this is teh device using the PPP command line util I can get modem information from such as:

      
      Current Time:  976          Temperature: 22
      Bootup Time:   1          Mode:        ONLINE
      System mode:   GSM             PS state:    Not attached
      GSM band:      GSM900
      GSM channel:   75
      GMM (PS) state:DEREGISTERED        PLMN SEARCH
      MM (CS) state: IDLE                NO IMSI
      
      Serving Cell:  75 (GSM 900    )
      RX level (dBm):-96.1875          LAC:         00A0 (160)
      GPRS State:    GPRS IDLE           Cell ID:     0000022A (554) 
      

      The rest of the error log snippet is below:

      Jan 1 01:17:41	ppp: [opt2_link0] CHAT: +CGDCONT=1,"IP","general.t-mobile.uk"
      Jan 1 01:17:41	ppp: [opt2_link0] CHAT: Detected Hayes compatible modem.
      Jan 1 01:17:41	ppp: [opt2_link0] CHAT: Dialing server at *99#...
      Jan 1 01:17:41	ppp: [opt2_link0] CHAT: ATDT*99#
      Jan 1 01:17:41	ppp: [opt2_link0] CHAT: Invalid dial init string.
      Jan 1 01:17:41	ppp: [opt2_link0] MODEM: chat script failed
      Jan 1 01:17:41	ppp: [opt2_link0] Link: DOWN event
      Jan 1 01:17:41	ppp: [opt2_link0] LCP: Down event
      Jan 1 01:17:41	ppp: [opt2_link0] Link: reconnection attempt 13 in 4 seconds
      

      Any help is much appreciated.

      Thanks

      1 Reply Last reply Reply Quote 0
      • stephenw10S
        stephenw10 Netgate Administrator
        last edited by

        Reading some blog and forum posts, possibly that modem needs atd instead of atdt to dial. No idea how you'd change that but maybe you could test it from the command line.

        Steve

        1 Reply Last reply Reply Quote 0
        • J
          jamest
          last edited by

          @stephenw10:

          Reading some blog and forum posts, possibly that modem needs atd instead of atdt to dial. No idea how you'd change that but maybe you could test it from the command line.

          Steve

          Thanks, I did wonder if it was something like that.

          I'll try that from the PPP term.

          1 Reply Last reply Reply Quote 0
          • First post
            Last post
          Copyright 2025 Rubicon Communications LLC (Netgate). All rights reserved.