Why is there no ring back on outbound calls?


This article provides information on where ringback is generated and provide potential work-around on the connections processing the call.


  • Ringback – An audible indication to the originator of a phone call that the destination is providing ringing.
  • 180 Ringing – Destination user agent received the INVITE, and is alerting the user of the call.
  • 183 Session Progress/Early Media – Indicates either that the called party is alerting, or may also be used to play any kind of audio file.


There are typically 2 reasons a caller will not receive ringback when placing an outbound call from the NetSapiens platform.

  1. The far end carrier is returning a 183 Session in Progress but is not transmitting any ringbackaudio to the system.
    1. Review the SIP Flow for a 183 Session progress, after the INVITE to the called destination.
    2. If the 183 Session Progress is present, select that leg by clicking on the arrow directly below the 183 Session Progress.  You will then see the details of the 183.
    3. Review the details for the “From” line. This will include the connection that is sending the 183.
      1. Example: From:“5554443322″[email protected]>
      2. The connection is
      3. One possible solution is to add the following rule to that specific connection: X183To180.


        This may cause problems when calling someone with a custom ringback tone, or if the destination is an auto attendant.

      4.   The far end carrier is returning a 180 Ringing, has included SDP in the 180 Ringing, but is not transmitting any ringback audio to us
        1. Review the SIP flow for a 180 Ringing, after the INVITE to the called destination.
        2. If the 180 Ringing is present, select that leg. You will then see the details of the 180.
        3. Review the details for Content-Type.
          1. While a carrier is technically allowed to include SDP in a 180 ringing, it’s a best practice not to. If a customer is complaining there’s no ringback audio but you see SDP present, it likely just means no ringback audio was transmitted to us.
          2. If sdp is present (Content-Type: application/sdp), move to next step.
          3. Review the details for the “From” line of the same leg. This will include the connection that is sending the 180.
      • Example: From:“5554443322″[email protected]>
      • The connection is
      • You will add the following rule to the connection:  DelSdpIn180.