Webhook action for Zoho CRM

We want a custom Webhook for integrating our Invoco telephone system with Zoho CRM.

Process
1. Call completion fired by Invoco to Zapier.
2. Zapier call our webhook passing data from Invoco
3. Webhook find contact
3.1 Search for contact with phone/mobile number matching Invoco payload
3.2 If found, skip to 4.
3.3 Search for lead with phone/mobile number matching Invoco payload
3.4 if found, skip to 4.
3.5 Create lead with contact number as no-one found
4. Webhook Add call entry to lead/contact in Zoho CRM
5. Webhook send email to lead/contact owner with link to call to update with notes

Webhook will be hosted on our own webserver.
Programming language: PHP

Zoho CRM API: https://www.zoho.com/crm/developer/docs/api/v3/modules-api.html
Example payload from Invoco: https://developer.invoco.net/#tag/Call