This event would tell the system to send telephony events of any phone or phone number under your account.

"/restapi/v1.0/account/~/telephony/sessions"

This event would tell the system to send presence and simple telephony status event of the extension that subscribed for the event.

"/restapi/v1.0/account/~/extension/~/presence?detailedTelephonyState=true"

You test phone or number must be under the account. Double check if you accidentally test your app in sandbox but using your production number or the other way around.

Thanks Phong, the issue was the test phone was not created in the sandbox environment. I appreciate your help!