VOIP calls have multiple recordings

When dealing with some VoIP systems, the calls can be split into multiple portions of audio.
the recording software tracks each portion and records them, if there is a party involved with the portion, that has been configured for recording.

Some times the VoIP system will redirect the call through a new network route or a new party joins the call and the recording may be stopped and a new recording started. This happens automatically, since the VoIP system will usually re-negotiate the communication between all the parties (extensions) involved in the call. This is to ensure that all the parties are still able to get through to each other.
then the call continues. This is usually so fast that people will not notice this.

Recording Scenarios:

  1. When a new call is started, some VoIP systems will setup multiple initial attempts to start a call and which ever responds first, will continue the call. All the other attempts are then stopped.
  • Multiple recordings are started.
  • The actual call will continue recording
  • The stopped calls may have a short recording, if there were audio packets generated and sent.
  • If there was any adio, Amethyst will record and process the file into the system.
    There are settings that we can enable on the VoIPSweeper to reduce the minimum duration that should be allowed into the system. But these short calls will be deleted if this facility is used.
  1. When a call is placed on hold and retrieved, the recording can be split into multiple recordings.
  • The first part of the call is recorded and may stop recording, if the specific VoIP system stops transmitting audio.
  • If the call uses encrypted Audio it may also stop recording, since the VoIP system may change the encryption keys when the call is retrieved from hold.
  • Another call may be made while the call is on hold, that will record on a separate recording, if the VoIP system treated it as a sperate stand alone call. Most systems works like this.

On Mitel CRE recording solutions, it is sometimes possible that a single call appears on multiple recordings. Usually the calls will slice into similar duration recordings if the call exceeds the keep alive timers.

  • Keep alive timer is 180 seconds.
  • Call is 600 seconds line.
  • First recording is 90 seconds long and contains all the call data and a Link ID.
  • The next 5 recordings are also 90 seconds and do not have Link IDs or no call details at all.
  • The last recording is 60 seconds long and may contain details again. The CRE does a final request for call details on the end of the call as well.

There is a re-invite that occurs on a timer between the two endpoints to keep the call alive. This re-invite is not supposed to change anything between the two end points to allow calls to continue flowing. But the Mitel does have a setting that will renegotiate the PORTs involved with this call if a re-invite is received.
This causes the Audio streams to initiate new sessions with the MBG and this causes recordings to slice into separate parts. There are new encryption keys and new sessions created.
Usually these are based on timer intervals from the Keep alive or half the keep alive time.

The Mitel setting that affects this is the one with the blue line in this image. (Repeat SDP Answer if Duplicate Offer is received)
This should send the same IP and port details to keep the call on the same connection.