How to protect contact numbers from leakage?

Question

Telephony

The task is to provide access to the contact details of customers to a person who is seasonally invited to work. The employee will constantly move around the territory of the enterprise.
Initial conditions
1) contact data is stored only in the cloud
2) retain the ability to dial relatives in the event of a medical emergency at any time
3) do not leak the customer contact database to the employee
4) eliminate the ability to take screenshots, copy paste.
Any designs are accepted.

Answer 1

The only option is to not show customer data on the screen. Show the "Call" button, by which the called number and employee number will be transferred from CRM to the PBX. And already the PBX should call back to both numbers and connect them for a conversation.

Answer 2

Do not display this person's contact information. In a certain interface, display only the full name and the "call" button (unload from CRM, make a simple web interface with access to the CRM database, or configure CRM so that it does not display contact information). When the button is pressed, the caller receives a call via callback on the mobile (we used Asterisk). Thus, a person can call anyone, but does not recognize their real numbers in any way.

Answer 3

2) maintain the ability to recruit relatives in the event of a medical emergency at any time

buy a telephone for pensioners
in a normal CRM access is regulated by the matrix of roles, they made a role - outlined the number of records, and - most importantly - the fields of records that are available