Unable to send message to end user (msteams) via Bot - json

Question

Facing issue to send proactive message to the end user (msteams), via bot service,
I try using the bot framework python SDK, where I am getting the following error even for getting conversation id.
botbuilder.schema._models_py3.ErrorResponseException: Operation returned an invalid status code 'Unauthorized'
Hence I try to simulate calls via postman and rest API's, in here I am able to get conversation id successfully, but if I try to use that conversation id to further send a message via activities I am not able to do it. following is rest endpoint and payload. In here I am getting an error of incorrect payload.
https://smba.trafficmanager.net/apis/v3/conversations/8:orgid:949a3f72-b82c-4b89-b2de-9defbe6ae7cd/activities
{
"type": "message",
"recipient": {
"id": "29:1ZcsKdk0rsLmsywvI2SNQ2J7OIz"
},
"from": "bot",
"channelData": {
"notification": {
"alert": "true"
}
},
"text": "Hello world"
}

Answer 1

There was an issue with payload, I added BOT_ID along with name and able to successfully post message to end user. Following is working payload.
Payload:
{ "type":"message",
"recipient":{
"id":"29:1dUxQXVlH6QGByu1T9MR4p5g0c5URMaBtKqGU74C3zdowO78nPbuu2dg- qj9o02OkJ4MYXt2I-nxDgf9ga9EY5w"
},
"from":{
"id":"28:d7afe8c9-f0cd-434f-8906-be2b744229ac",
"name":"bot"
},
"channelData":{
"notification":{
"alert":"true"
}
},
"text":"Hello "
}