Mobile operators use a variety of ways to monitor termination of calls. It is known that there are certain "humanity parameters", which AntiFraud systems use as indicators to track operating gateways. Operators make calls to SIM- suspected in the GSM traffic termination before they lock them. Calls are made through the VoIP network, and if a call is successful, the card is blocked immediately.
Every terminator wants to find a solution that would allow the fight operator calls. However, it is impossible to resolve this problem completely since providers can call at any time and from any number. There are preventive measures, using which you can minimize the risks of operator calls and subsequent blocking of SIM-cards.
The use of SIM-cards that have "history"
If you use the cards issued to real people and having some "history" in the GSM-network for the GSM traffic termination, you can significantly reduce the risks of locking. AntiFraud systems more closely monitor anonymous and just activated cards.
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A gradual increase in the activity of SIM-cards
You can also reduce the probability of operator calls if you increase the SIM-card activity gradually after it is activated. If the card is actively used, terminating numerous calls, it is going to attract the cellular provider's attention. It is best to build up the termination logic so that conducted traffic is distributed among all the cards.
Filtering the numbers
Many terminators filter calls to prevent operator calls. That is, they remember which number makes a call with the subsequent blocking of the card, and mark it for themselves as the one that belongs to the operator. Repeated calls from this number to the other SIM card are rejected.
In order to minimize risks of operator calls, you can use GoAntiFraud. Creating "black" and "white" lists enables effective filtering of incoming and outgoing calls. The "black" list included numbers, which allegedly belong to the operator. They can be entered in the list manually or generated using certain parameters. Incoming and outgoing calls to these numbers will be automatically rejected. In the "white" list, you can enter the numbers that the terminator trusts in. Outgoing calls will be rejected if they are made to the numbers that are not on this list.
An additional advantage of using GoAntiFraud lists is the ability to filter voice traffic. With access to comprehensive statistics on the SIM-cards, you can determine the numbers with low ASR and ACD. By incorporating them into the "black" list, you will provide a more efficient GSM termination, by rejecting zero and short calls.