Ans. The legality of using a reverse phone number lookup service varies by jurisdiction. In many places, it's legal to use such services for personal or non-commercial purposes, like finding contact information. However, using it for harassment, stalking, or other malicious activities is illegal. Additionally, some countries have stricter privacy laws that may restrict the use of reverse phone lookups without consent. Always ensure you comply with local laws and terms of service of the specific lookup service you're using. Unauthorized use for telemarketing or unsolicited calls may violate laws like the Telephone Consumer Protection Act in the United States.