Policy Recording Bot not joining the call

Hi,

I have used below repository code to setup Compliance Recording Bot and running locally. Its endpoints are exposed publicly and are accessible over the internet.
https://github.com/microsoftgraph/microsoft-graph-comms-samples/tree/master/Samples/V1.0Samples/LocalMediaSamples/PolicyRecordingBot

Endpoints:
https://{domain}/logs
https://{domain}/api/calling/
https://{domain}/api/calling/notification

I have done below steps already:

• I did an app registration with following permissions with admin consent:
  CallRecords.Read.All
  Calls.AccessMedia.All
  Calls.Initiate.All
  Calls.InitiateGroupCall.All
  Calls.JoinGroupCall.All
  Calls.JoinGroupCallAsGuest.All
  OnlineMeetings.ReadWrite.All
  User.Read
• I did register a bot in the Azure Bot Service with following Webhook (for calling)
  https://{domain}/api/calling/
• Created an Application Instance using below commands
  Import-Module MicrosoftTeams
  Connect-MicrosoftTeams
  New-CsOnlineApplicationInstance -UserPrincipalName upn@contoso.com -DisplayName -ApplicationId <your_botappId>
  Sync-CsOnlineApplicationInstance -ObjectId
• Created a Recording Policy using below commands
  New-CsTeamsComplianceRecordingPolicy -Enabled $true -Description "Test policy created by "
  Set-CsTeamsComplianceRecordingPolicy -Identity -ComplianceRecordingApplications ` @(New-CsTeamsComplianceRecordingApplication -Parent -Id )
  Get-CsTeamsComplianceRecordingPolicy
• Assigned the Recording Policy to a user
  Grant-CsTeamsComplianceRecordingPolicy -Identity userUnderPolicy@contoso.com -PolicyName
  Get-CsOnlineUser userUnderPolicy@contoso.com | ft sipaddress, tenantid, TeamsComplianceRecordingPolicy

Testing Scenario:

• Sign in to Teams client with a non-recorded test tenant user.
• Use another Teams client to sign in with the recorded user. You could use an private browser window and open up https://teams.microsoft.com.
• Place a call from the Teams client with the non-recorded user to the recorded user.
• Your recording bot should receive the incoming call and join the call immediately.

Problem/Issue:
My bot is not receiving any notification request and not joining the call.

Start with the PolicyRecordingBot sample under Samples/V1.0Samples/LocalMediaSamples/PolicyRecordingBot and inspect the exposed /logs, /api/calling/, and /api/calling/notification endpoints. Reproduce the listed Teams call scenario and check whether notification requests appear; done means the bot receives the incoming call notification and joins the call.