How to implement a virtual number with call forwarding and number substitution?

Question

Telephony

It is necessary to advise a service or other implementation, thanks in advance.
There are 8 mobile numbers: + 7 (927) 33-15-409, etc.
These numbers can also be virtual: with area code + 7 [phone]
There are incoming calls to these phone numbers.
You need to do the following:
For example: when you receive an incoming call to + 7 (927) 33-15-409 (or virtual: + 7 [phone]), you
are forwarded to another mobile / virtual number, (in priority - mobile) - 927-77-11-321
THIS
NUMBER will not be visible to the real client (927-55-55-777), but a substitute
number (927-33-33-111), which will be
assigned to each calling client by principle 1 client - 1 replacement number.
a) this replacement number (927-33-33-111), you can: listen and view in special. table,
when an outgoing call is made to it from any number, a connection must be established with the real client number (927-55-55-777) for a conversation.
b) as described above, listen and view in special. table a substitution number (927-33-33-111), with an incoming call from a client, initially to the main number (7 (927) 33-15-409). Here, as an option, you can listen not to a replacement number, but to the number to which the call is forwarded from the main 7 (927) 33-15-409, i.e. the number is 927-77-11-321.
c) it is planned to process up to 50 calls per day, the transaction life cycle is 1 week. In total
, about 350 numbers will be required. Customer number life cycle = 7 days.
PS The technical organization can be different - the most important thing is to keep the logic of the system.

Answer 1

I will briefly describe the logic of the system:
From the main number there is a transfer to the "other" number, while the true number is replaced by the "replacement" = the ability to listen to the "other" number.
When dialing from any numbers to a "substitute" number, the call is redirected to the "true" number. = ability to listen to "substitution number"