Is there a good free or shareware alternative to Google Contacts?

Question

Contacts

Now I have taken on a voluntary basis for one rather interesting project related to the contact base of all employees of the organization.
Main idea.
Creation of a dynamic corporate contact base of all employees. All calls that come and go from work phones during working hours between employees must be signed in the same way for everyone (single standard). Work phones should not have unknown / unsaved numbers. It looks like total control, but in reality it is an Ideal notebook .
If you look into the phone directories of each person, you can see that many contacts are saved as convenient for remembering, however, almost everyone has a contact "Mom", "Dad", "Brother / Sister" and many other contacts that are the same for everyone, but the rest, alas, people write down and remember in different ways. Sometimes they don’t save numbers at all, but remember by eye and look in the call log, and all because it’s difficult / no time to poke a couple of buttons. And if the phone gets lost or turns off and there are no contacts And what if the account to which the contacts are linked has become unavailable (they forgot the password), and I generally don’t take the SIM card seriously in this regard. In general, the problem with contacts is different for everyone. What I describe will solve problems with numbers, and introduce everyone to everyone. For any question,

What I have now
1) There is a database of contact data of employees, at the very least collected by the personnel department and the support service, that is practically not involved in any way.
2) The ability to manually enter all contacts into a specially created Google Account, for dynamic management of the contact base, for all those who connect this Account to themselves. (Any number will be immediately recognized and you can see who is calling, you can add a photo in the future)
3) The ability to check contacts on several Androd devices (IOS does not seem to support this, but there are a lot of these devices)

Found and future problems using a Google account with contacts
1) It is not possible to insert contact data directly from tables and importing from other formats. You have to manually correct.
2) Google Account (possibly) synchronizes with its database those contacts that were already in the device. (Maybe there somehow you can set up synchronization so that it is one-way)
3) Duplicates directly from people who connected the Account with contacts.
4) Lack of support for Google contacts in the usual form for IOS devices.
5) Difficulties with constant synchronization of contacts (When there are more than 1000 contacts, and the Internet is so-so, there may be interruptions and glitches.)

Preliminary results
Now, at the current stage, I am experiencing moral difficulties, because. These problems are easily outweighed by not too big pluses. The benefits of using a dynamic corporate contact database. The simplest option that would greatly simplify life is the normal transfer of contact data from Excell to any service like Google Contacts.

Answer 1

everything is imported
https://support.google.com/contacts/answer/1069522...
otherwise, the norm
is now on the case: the database is maintained by the personnel officer in Excel ON TOP
, you can screw anything into any 1C
of the contact server called https://en .wikipedia.org/wiki/CardDAV but you need to think three hundred times whether the introduction of such and support is not empty talk