Passing data to Outgoing webHook URI

The request data passed to the Outgoing WebHook script (direct message channel) contains the following data:

“token”: “78zvSW24Haca8DbKke2Zp9CX”,
“bot”: false,
“trigger_word”: “sendsms”,
“channel_id”: “NLgJ87tufbRKT93dutwL2S9jHn8iee8jaY”,
“message_id”: “3Wz6rZoM58qKdYMFp”,
“timestamp”: “2021-03-17T18:09:18.178Z”,
“user_id”: “twL2S9jHn8iee8jaY”,
“user_name”: “John_234”,
“text”: “sendsms test”,
“siteUrl”: “
Note, there is no channel_name. The name of the user who triggered the action is ‘John_234’,
How can I retrieve the name of the other peer on the channel?
The goal is to send SMS from user A to user B
Thank you!