Not able to interact with calling meeting bot and receive "502 Bad Gateway" error

[JessicaLu85]

I downloaded samples from https://github.com/OfficeDev/Microsoft-Teams-Samples

For bot-calling-meeting c# sample, I registered a new bot with https://dev.botframework.com/bots/ according to https://docs.microsoft.com/en-us/microsoftteams/platform/bots/calls-and-meetings/registering-calling...

I modified appsettings.json and manifest.json, then debug in Visual Studio with "Your bot is ready!"

then I test with web teams of the bot, I cannot interact with the calling-meeting bot and I can see "There was an error sending this message to your bot: HTTP status code BadGateway"

also I'm reading the step-by-step guide from https://docs.microsoft.com/en-us/microsoftteams/platform/sbs-calling-and-meeting?tutorial-step=1, I cannot interact with the calling-meeting bot either. no welcomeText with Adaptive Card and when clicking video/audio call button I will receive "you can't talk to the bot just yet"

I can see 

"POST /api/messages 502 Bad Gateway

 POST /api/callback 502 Bad Gateway " from the console

Could anybody tell me what's my problem and how to resolve this? Thanks

[#2]

@JessicaLu85 -Check if you had created policy for that tenant user.

Please make sure you have enabled calling and configured proper endpoint on Teams channel page. 

[#3]

Hi @Sayali-MSFT , thanks for your reply!

you mentioned "Check if you had created policy for that tenant user"--Could I know what kind of policy, actually I have no extra policy set for the tenant user during configure the bot except the online meeting policy mentioned in https://docs.microsoft.com/en-us/microsoftteams/platform/sbs-calling-and-meeting?tutorial-step=2

I have configured webhook for calling as below picture:

[#4]

@JessicaLu85 -Could you please try in webhook url instead of /api/callback use /callback as mention in my screenshots.

[#5]

Still no good luck :(
no welcomeText with Adaptive Card after adding the app, this time no video/audio call button either
I can see
POST /api/messages 502 Bad Gateway OPTIONS /api/messages 502 Bad Gateway

[#6]

@JessicaLu85 -We are unable to repro the scenario. It's working fine from our end. Could you please Ensure that you've enabled the Teams Channel.

and also check the While registering the bot, use https://<your_ngrok_url>/api/messages as the messaging endpoint and port.

[#7]

@JessicaLu85-Could you please confirm if your issue has resolved with above suggestion or still looking for any help?

[#8]

Sorry for late reply as not able to use internet for a long time. I'm not able to resolve this problem using https://<your_ngrok_url>/api/messages as the messaging endpoint : (