Hi @kmarimuthu,
Thanks for your patience so far!
So, actually the "resource" name here is "telephony_calls", not the "telephony_push". That's why you're currently seeing the error.
It'a actually not your mistake, it's true that it's still not documented well in the Webhook API page, though it's actually properly described in Webex Developer Portal Webhook documentation here - https://developer.webex.com/docs/webhooks
Since there is no specific section for this Calling Webhook on that provided page URL, please search for the keyword "telephony_calls" in that page and you'll get the details.
Hope that'd help you.
Also, please note - currently this "telephony_calls" webhook only supports under Account or, Personal level. It currently doesn't support Org level. There is a public feature request is also raised for it - https://ciscocollabcustomer.ideas.aha.io/ideas/WXCUST-I-8154
Hope this helps!
Please let us know for any further assistance.
Regards!
Sandip
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