The main problem You face when operating a call termination business, is SIM blockage. Cellular providers keep blocking SIM cards for what they consider "excessive use", forcing You to buy more and more SIMs, which turns to a major drain on Your revenue. To help you combat that, there are several features installed into the Gateway.
Call & minutes Counters and SIM Auto Manage:
The VoIP Gateway has a page which shows the amount of minutes and number of calls made through each SIM of each cellular module. The SIM Auto Manage feature, which enables You to swap the active SIM in the cellular module, will use the information in that page. Each cellular module can have up to 4 or even up to 10 SIMs (depending on the cellular card's model). You can choose to have a module switch to another of its SIMs after 15 minutes of cumulative talk-time or after 25 completed calls, whichever comes first. You can also configure the module to altogether remove the SIM from the roster. For example - You can configure the module to use another SIM after 15 minutes and disable it after 90. The module will swap to another SIM every 15 minutes of talk-time until it has used them all and will do so for 6 times - 15X6=90 - at which point You'll need to reset the counters and re-enable the SIMs.
IMEI changer (EMS+):
The Gateway has an optional module that will enable You to assign a different IMEI to each SIM, so the module will assume a different identity when swapping to that SIM. That way it will not show a single cell phone using 10 different SIMs, but rather 10 cell phones, working at different times, which is normal activity.
Voice calls generator (VCG+):
The Gateway also has an optional feature that allows You to make calls between the different modules, thus showing it's not only dialing them, but also accepting them, further giving the appearance of regular human behaviour.
Channel Binding - the Gateway will try and dial calls to the same number go out the same module, making it seem that there is regular traffic between two cellular phones, just like in every day communications - by and large - phones call to the same numbers. Each SIM has a sort of address book with numbers it has dialed in the past. A number can appear in several modules' address book and You can limit the amount of concurrent calls, so there's more of a chance it will have a module available to complete a call to that number.
Dynamic Black List - block destination numbers or calling numbers if they are below a certain length or have a low call completion rate.