Truecaller identifies unknown callers and blocks spam, a real relief in Pakistan where telemarketers and scam calls are constant. Its crowd-sourced spam database flags suspicious numbers before you pick up. Pros: reliable caller ID for unknown numbers, effective spam and scam call blocking, call recording and SMS filtering built in. Cons: needs broad contact and call-log permissions to work well, free version shows ads and reserves some features for Premium. Best for people tired of spam calls and unknown-number anxiety.