I don't know what programming language you are using so just assumed that you are using Node JS. If not, check out other languages under the same category.
First of all, get familiar with Webhook by following the quick start guideline from the link below
https://developers.ringcentral.com/guide/notifications/quick-start/webhook/node
Then, replace the event filter
eventFilters: ['/restapi/v1.0/account/~/extension/~/message-store/instant?type=SMS']
with
eventFilters: ['/restapi/v1.0/account/~/presence/?detailedTelephonyState=true'],
With this event filter, you can get notification for all extensions (users) under the account. If you have a list of users whom you want to monitor, specify a list of event filters instead. E.g.
eventFilters: [
'/restapi/v1.0/account/~/extension/[EXTENSION_ID]/presence/?detailedTelephonyState=true',
'/restapi/v1.0/account/~/extension/[EXTENSION_ID]/presence/?detailedTelephonyState=true',
'/restapi/v1.0/account/~/extension/[EXTENSION_ID]/presence/?detailedTelephonyState=true'],
Remember that you need to login the app with an admin user role.
