The most common reasons a call is blocked or flagged are that: Consumers reported your number as spam. Using call-blocking apps or the native software on their smartphone, consumers can report numbers they believe to be a spam or scam risk. If a significant number of people report your number, it may be flagged or blocked entirely. Carriers flag your number due to frequent dialing. If the same number is used too much in a given period, carriers may flag it as suspicious. (In rare cases, carriers may choose to block an overused number altogether.) Because carrier algorithms cannot tell the difference between a malicious and legitimate caller, they typically rely on high-volume numbers with predictable dialing patterns. Convoso recommends placing a maximum 50-75 calls per phone number per day, when possible.