Channel Messaging Limitations
WhatsApp Business API (WABA) https://developers.facebook.com/docs/whatsapp/api/messages#faq
https://developers.facebook.com/docs/whatsapp/api/rate-limits/
https://developers.facebook.com/docs/whatsapp/api/media/
Facebook Messenger https://developers.facebook.com/docs/messenger-platform/reference/send-api#limits
https://developers.facebook.com/docs/messenger-platform/send-messages/#limits          
https://developers.facebook.com/docs/messenger-platform/send-messages/#sending_attachments
Telegram https://core.telegram.org/bots/faq#handling-media,
https://core.telegram.org/bots/faq#broadcasting-to-users
WeChat https://developers.weixin.qq.com/doc/offiaccount/en/Message_Management/API_Call_Limits.html https://developers.weixin.qq.com/doc/offiaccount/en/Message_Management/Batch_Sends_and_Originality_Checks.html
LINE https://developers.line.biz/en/reference/messaging-api/#rate-limits
Viber https://developers.viber.com/docs/api/rest-bot-api/#message-types
Microsoft Teams https://docs.microsoft.com/en-us/microsoftteams/limits-specifications-teams
Slack https://slack.com/intl/en-sg/help/articles/115002422943-Message-file-and-app-limits-on-the-free-version-of-Slack#:~:text=Members%20can%20send%20unlimited%20messages,your%20direct%20messages%20when%20searching
Cisco WebEx https://help.webex.com/en-us/n8vw82eb/Webex-Capacities
WeCom (formerly WeChat Work) https://developers.weixin.qq.com/doc/offiaccount/en/Message_Management/API_Call_Limits.html https://developers.weixin.qq.com/doc/offiaccount/en/Message_Management/Batch_Sends_and_Originality_Checks.html https://work.weixin.qq.com/wework_admin/app_comm_intro?ver=3.0&type=mng&from=intro_list&lang=en
sendQuick ASP (SMS) Outgoing SMS message throughput rate: 10 SMS/second

Incoming SMS: currently not supported for SendQuick.io services