to send a message (or call) to a phone number the sender of the message has to pay the company that owns the recipient number a fee. the fee varies. in the u. s

to send a message (or call) to a phone number the sender of the message has to pay the company that owns the recipient number a fee. the fee varies. in the u. s. it’s very small. less than a penny. in some undeveloped countries it’s much higher. most fraud like this occurs in those countries with higher fees let’s say i make friends with a mobile network operator in a country with high fees. i tell that mobile network i can send a lot of traffic to your network and generate you revenue in message passing fees. but i need to get a share of the money. the mobile network operator understands my methods are not legit and will not block the traffic / apply normal spam / anti fraud protections. we both make money at the expense of the message sender