4 Replies Latest reply on Feb 18, 2013 11:22 AM by david

    Modem Configuration for Mailing Machine

    mcdeeiis New Member

      Does any one has a working modem configuration. I have a mailing machine IM-440. It has the following settings..



      interface fxs 0/3

        impedance 600r

        ring-voltage 70

        no shutdown



      voice user 1234567890

        connect fxs 0/3

        first-name "Shipping-Dept"

        last-name "MODEM"

        password "xxxx"

        sip-authentication password "xxxx"

        rtp packet-delay fax 70

        alias 2345678901


      When I try to connect to the mailing server, it dials and then after awhile say Connection Failed. I have a sip stackmsgs if you need.




        • Re: Modem Configuration for Mailing Machine
          david Employee



          Thanks for posting!  Others on the forum may reply with working configurations, however many of these situations are unique.  I would first verify that you have no errors on any interfaces on the Adtran unit.  Next, verify that the all network devices between the RTP endpoints, including the Adtran unit, have QoS enabled if real-time and regular data traffic share those links.


          I would then change your voice user configuration to include "modem-passthrough" and omit "ring-voltage 70" unless you have determined that it is necessary for inbound calls.  Lastly, I would specify a codec for this voice user so that it starts outbound calls on G.711 only.  Below is an example.


          voice codec-list 711

            codec g711ulaw


          voice user 1001

            connect fxs 0/1


            codec-group 711



          We can then check the network performance with "show voice quality-stats".  It's important to note that some statistics, particularly the lost packets, can be improperly reported if the RTP sequence number is not consistent from the far end for the duration of the call.  Below is an example of a voice call followed by a fax/modem call.


                      Start                                                                Lost  Discard  Delay

          ID      Time          From      To        Duration Codec Pkts  Pkts            Avg    Max


          1964    8:38 AM  9001      2125      0:30    G729        0        0            80    100

          1965    8:38 AM  9001      2126      2:29    G711u      0        0            50    50


          For the fax/modem call, you should see the average and maximum delay at 50ms.  This is because a call in which fax tones are detected will switch to a fixed 50ms jitter buffer.  However, the normal phone calls can give us clues about network performance.  In a network with low delay and jitter, they normal phone calls will stay with the 50ms jitter buffer.  However, as shown in the example above, increasing delay indicates that the adaptive jitter buffer increased due to excessive jitter.  In general, faxing becomes unreliable when network jitter forces the jitter buffer to enlarge to greater than 70ms for non-fax calls.  However, values slightly higher than 50ms may help us determine static jitter buffer recommendations.  Let us know if you would like us to review the output of "show voice quality-stats" from your unit.



          We would then capture the following debug output for a given test call.



          debug sip stack message

          debug voice verbose

          debug int fxs



          In particular, we will be looking for what codec is being used, what fax/modem tones, if any, were detected, and if a Re-Invite was sent by either party.  If you would like us to review the voice quality statistics or your test call debug output, you may need to create a regular support ticket.  Otherwise, just make sure you do a find and replace so that customer IP addresses and phone numbers are removed from the log.



          Thanks again,


          • Re: Modem Configuration for Mailing Machine
            david Employee



            I went ahead and flagged the "Correct Answer" on this post to make it more visible and help other members of the community find solutions more easily. If you don't feel like the answer I marked was correct, feel free to come back to this post and unmark it and select another in its place with the applicable buttons.  If you still need assistance, we would be more than happy to continue working with you on this - just let us know in a reply.