Audio Stream Fields

The audio streams are encoded as 16-bit little-endian PCM, then Base64-encoded and transmitted to the third-party platform in JSON messages. This topic describes the fields in the JSON message transmitted via WebSocket.

Field Description

Field Description
channelid The call channel ID of each party in the call.
callid The unique ID of the call.
callflow Call scenario.
Note: If the field is empty, it means the call does not match any of the scenarios listed below.
  • ivr
  • queue
  • ringgroup
  • cfd
  • conference
  • multicast_paging
number Caller ID of the call.
status The current transmission status of the audio stream.
  • process
  • end
audio The audio payload containing PCM-encoded voice data for the call.
Tip: To obtain additional call details, use the callid provided in the audio stream packet to query the information via the API. For more information, see Developer Guide - Query Calls.

Example

According to the number of call parties, the audio transmission methods differs.
JSON message for a one-on-one call
For a one-on-one call, the PBX establishes a single WebSocket connection with the third-party platform and interleaves audio fragments from both call parties over this connection, using two logical channels identified by channelid.
  • The call is in progress.
    • Channel 1
      {
    "callid":"1755940023.7"
    "callflow":""
    "audio":"UkSDFj82nJKLm90qweRTyVxZaBcDeFgHiJkLmNoPqRsTuVwXyZ1234567890ABCD..."
    "number":"1009",
    "status":"process"
    "channelid":"P]SIP/1009-XXXXX005'
}
    • Channel 2
      {
    "callid":"1755940023.7"
    "callflow":""
    "audio":"WHRTb2Z0d2FyZQBBZG9iZSBJbWFnZVJlYWR5ccllPAAAA..."
    "number":"1010",
    "status":"process"
    "channelid":"P]SIP/1010-XXXXX006'
}
  • The call ends.
    • Channel 1
      {
    "callid":"1755940023.7"
    "callflow":""
    "audio":""
    "number":"1009",
    "status":"end"
    "channelid":"P]SIP/1009-XXXXX005'
}
    • Channel 2
      {
    "callid":"1755940023.7"
    "callflow":""
    "audio":""
    "number":"1010",
    "status":"end"
    "channelid":"P]SIP/1010-XXXXX006'
}
JSON message for a multi-party call
For a multi-party call, the PBX establishes a dedicated WebSocket connection with the third-party platform for each call party, sending their individual audio fragments separately.
Note: If a multi-party call is escalated from a one-on-one call, the PBX switches from a single WebSocket connection to multiple independent connections with the third-party platform, while preserving the same channel_id for each original party and call_id in JSON messages.
The following example illustrates JSON messages of a three-party conference in which each call party's audio is streamed over a separate WebSocket connection.
  • The call is in progress.
    • Channel 1
      {
    "callid":"1769052671.54"
    "callflow":"conference"
    "audio":"Lm90qweRTyVxZaBcDeFgHi5ccll..."
    "number":"1000",
    "status":"process"
    "channelid":"PJSIP/1000-XXXX0020'
}
    • Channel 2
      {
    "callid":"1769052671.54"
    "callflow":"conference"
    "audio":"HiJkLmNoPqRsTuVwXyZ1234567890ABCD..."
    "number":"1001",
    "status":"process"
    "channelid":"PJSIP/1001-XXXX0021'
}
    • Channel 3
      {
    "callid":"1769052671.54"
    "callflow":"conference"
    "audio":"WHRTb2Z0d2FyZQBBZG9iZSBJbWFnZVJlYWR5c..."
    "number":"2131005",
    "status":"process"
    "channelid":"PJSIP/2131005-XXXX0022'
}
  • The call ends.
    • Channel 1
      {
    "callid":"1769052671.54"
    "callflow":"conference"
    "audio":""
    "number":"1000",
    "status":"end"
    "channelid":"PJSIP/1000-XXXX0020'
}
    • Channel 2
      {
    "callid":"1769052671.54"
    "callflow":"conference"
    "audio":""
    "number":"1001",
    "status":"end"
    "channelid":"PJSIP/1001-XXXX0021'
}
    • Channel 3
      {
    "callid":"1769052671.54"
    "callflow":"conference"
    "audio":""
    "number":"2131005",
    "status":"end"
    "channelid":"PJSIP/2131005-XXXX0022'
}