Is there a mobile CRM with ip telephony for incoming/outgoing calls directly from an employee's smartphone?

Question

CRM

Objective: To organize the mobile operation of the processing center for incoming applications throughout the country.
It will look like this. There is a service, it has branches in several cities of the country. Applications fall to each branch through the site, which must be processed by the regional assigned manager (by phone) and transfer the finished deal to another business.
At the first stage, I see it like this:
You need CRM, with a mobile application and IP telephony integration. A new employee can download an application on his smartphone, get an account for the CRM - and voila - now he is a representative of his city. He is assigned a specific number from which he can make / receive calls through the CRM mobile application.
Also, all new requests from the service site of his branch fall to him. He processes them, calls directly from the CRM via IP telephony, indicates statuses, transactions and comments.
The employee has changed - just delete him from the CRM and give access to the new one, while maintaining the previous number and all transactions.
Those. the main idea is to completely refuse calls tied to the SIM card number in the phone. So that everything is like on desktop clients in popular CRMs, but only mobile. (I'm talking about leads and the ability to make and receive calls via IP telephony)
Oddly enough, but Bitrix24 almost came up. You can easily buy a virtual number from him and assign it to a specific employee. Everything works great on desktop. In the mobile application, there is no such function, you can only call using the phone, Skype or other third-party messengers.
Does anyone have any ideas what to use? Basic functionality required.
PS Why do you want so zealously to pass everything through IP telephony? Well, also in order to have a record of all incoming outgoing calls in order to control the quality of work with applications from regional managers.

Answer 1

And why is Asterisk bad for a similar purpose?
In addition, as far as I understood the questioner: The regional manager puts any SIP dialer on the phone, it indicates the server and the Asterisk login / password, and now the calls are already going through it. The record is there. For city numbers, we connect to one / several VoIP providers. All that's left is CRM. I don’t know here, but I think there are a lot of CRM compatible with Asterisk.

Answer 2

https://42clouds.com/ru-ru/products/stream.html now works within the company, more than 350 employees, telephony works at 4+