Mеждинен вариант - слагаш един gsm gateway с изход аналогов и включваш телефона със шайбата.

ПС. Телефона със шайбата може и да не работи, но такъв с тонално набиране да.

SIM Bank is another name for the SIM box which is a hardware-based network device that has the capability of reading a bank of SIM cards. It then establishes a virtual connection between SIM cards and GSM based devices to allow them to communicate. The SIM bank allows for a large number of SIM cards to be installed in a single location but allows for the GSM-based devices to be installed at variable locations. This is also called remote SIM card management through SIM bank.

SIM bank can’t directly communicate with GSM-based devices but instead communicates using VoIP gateways with remote SIM card support. The device (SIM bank) aggregates multiple SIM cards in a single location and their connection to the GSM gateway is carried via an IP network. So the power of the internet is utilized for the purpose of establishing communication between the SIM cards and GSM gateway. The key is VoIP Gateway.

SIM cards belonging to different service providers can be inserted into the same SIM bank and still be used simultaneously. The SIM bank serves a variety of different functions including:

Using a single device, the operator can have a centralized system for the management of any number of SIM cards.
It allows for instant or rapid installation of any SIM card by simply inserting it into a slot. One SIM card can easily be swapped for another; the process is called Hot Swapping.
The device itself is capable of a proper and just distribution of SIM cards between different GSM gateways. The distribution can also be set according to temporary rule.
On certain events, a SIM bank ensures the automatic distribution of SIM cards on different GSM gateways distributed by the criteria of time or event.

With the help of a SIM bank, an operator can easily swap SIM cards at their disposal to change gateway locations on distributing GSM gateways throughout a city creating the illusion of a subscriber on the move which promptly reduces the chance of being detected by the service provider and getting blocked.