CRM is an online SaaS service hosted by cloud servers in large data centers. SSL protocol ensures secure data transmission. The data undergoes recurrent backup. Data and server access is strictly limited and is only available to the engineering department management. Access permissions distribution is the prerogative of your CRM administrator only.
You can flexibly adjust user access permissions for various types of contacts/deals/objects, allow department managers to view the tasks of their subordinates and browse their calls history, including conversations recordings. It is also possible to restrict the viewing/editing access to certain fields of contact profile, for instance.
You can restrict access to the CRM by IP address: for example, deny the system access from any IP different from the one in your office.
APRO CRM also allows data backup in email or FTP format.
In addition, you can enable logging to register all user activity in the CRM. Logs allow CRM administrators to monitor the users opening or editing certain contact/object/deal/etc. profiles. 
Q & A
Is it possible to set the phone number in a contact profile visible to the contact supervisor and the manager only and hide it from all the rest?
Yes, just use the access settings. You can also grant/restrict access to any field in contact/deal/object/activity profile.
Can I check which users edited a contact profile during a certain time frame?
Yes, enable logging to see all the events and activity involving a certain contact for a given time frame. Logs will also give you a full picture of all user activity throughout the CRM (involving any CRM elements).
Can I restrict access to the CRM from anywhere different from the office for everyone, except the administration?
Yes, you can basically introduce two rules: one rule restricting access from any IP different from the office one, and the other rule allowing access from any IP for the administration.
APRO CRM is a SaaS cloud solution and is hosted by our servers. The CRM is flexible and can adjust to your business needs. You will be getting all the necessary assistance from your personal adviser while using the system