Teams媒体机器人加入会议失败：错误500#1203002求助

我正在构建一个Teams媒体机器人，以访客身份加入已安排会议，实现音频流传输和转录功能。向/communications/calls发起POST请求后，呼叫成功创建，但在establishing阶段终止，报错：

ServerInternal Error. DiagCode: 500#1203002.@

已尝试的排查步骤：

• 验证证书有效性及与FQDN的绑定
• 通过Azure NSG、VM防火墙及外部Nmap扫描确认端口（如8445 TCP/UDP）已开放
• 确保请求Payload符合文档要求，包含appHostedMediaConfig blob及allowConversationWithoutHost: true
• 已授予并同意应用权限

附Graph请求Payload：

{
  "@odata.type": "#microsoft.graph.call",
  "direction": "outgoing",
  "callbackUri": "https://accuremd.eastus.cloudapp.azure.com/mediabot/notifications",
  "requestedModalities": ["audio"],
  "mediaConfig": {
    "@odata.type": "#microsoft.graph.appHostedMediaConfig",
    "blob": "{\"mpHttpUri\":\"https://accuremd.eastus.cloudapp.azure.com/MediaProcessor/v1\",\"supportedAudioFormat\":\"Pcm16K\",\"audioSinkEncodingFormats\":[\"PCM\"],\"audioSourceEncodingFormats\":[\"PCM\"]}"
  },
  "chatInfo": {
    "@odata.type": "#microsoft.graph.chatInfo",
    "threadId": "19:meeting_OGJjZDg3NjYtMTE0NS00MWI2LTkxYTUtNTc3NjRlMmNjMjM1@thread.v2",
    "messageId": "0"
  },
  "meetingInfo": {
    "@odata.type": "#microsoft.graph.organizerMeetingInfo",
    "organizer": {
      "@odata.type": "#microsoft.graph.identitySet",
      "user": {
        "@odata.type": "#microsoft.graph.identity",
        "id": "5f2cd7d6-fad4-4770-9c2e-6a461872fd6a",
        "tenantId": "653f2dfa-0545-4c9f-be75-7c35da274877",
        "displayName": "AccureMD Media Bot"
      }
    },
    "allowConversationWithoutHost": true
  },
  "tenantId": "653f2dfa-0545-4c9f-be75-7c35da274877"
}

内容的提问来源于stack exchange，提问作者Dupesh Nayak