Remote connection to the phone file system

I've studied how it is possible to access the file system of a phone using something like phone number, IMEI number or other identification number of the same way that I can SSH or FTP in a computer if I have its IP address. I've found various Cisco resources such as cucm / ta-p / 3109183 and

But I was wondering if anyone knew the specific answer to that question. I know that it is possible to remotely access the file system and the operating system of a phone with the help of a protocol.