How to work with a large number of SIM cards?

Question

mobile connection

Hi all.
The task is as follows:
Implement a system of 100 SIM cards that must receive incoming SMS, merge them to a remote server
Implement a proxy server on each SIM card via the operator's Internet.
So far I see several implementations:
1. USB hub + modems, but I don’t know how to manage it all
2. A bunch of phones on android, it’s already easier with raising a proxy and sending sms to http (solutions), but there is no solution yet how to connect to them ( to proxy), probably via ddns
3. There are devices called GoIP for telephony, but I'm not sure if they support modem mode (only sms and calls)
4. There is a SIM server, but at the output they cling via USB and emulate X com ports and each module is controlled separately by AT commands, again it is very difficult and it is not clear how to manage
it. Of course, you can take GoIP and refuse to implement proxy servers on the side SIM cards, but then the cost of project implementation increases, while it is cheaper to take 100 phones.
Please advise the correct solution.

Answer 1

4. - the easiest.
1. - the cheapest.

Answer 2

We use goip gateways + sms server. The cost of the system is equal to the cost of the goip gateway.