Following are some websites that provides free, anonymous, temporary phone numbers without sign up hassle:
https://smsnator.com/ : US and Canada only.
https://receive-smss.com/ : India, UK, US, Ukarine, Austria, Poland, Czech Republic, Sweden, Netherlands, Canada, Croatia, Nigeria, Germany, Kazakhstan
https://sms24.me/ : Austria, Australia, Belgium, Canada, Czech Republic, Croatia, China, Estonia, France, Georgia, Germany, Hong Kong, India, Indonesia, Israel, Kazakhstan, Macao, Malaysia, Mexico, Mayanmar, Nigeria, Netherlands, Nigeria,, Philippines, Poland, Puerto Rico, Russia, Serbia, SA, Sweden, Ukraine, UK, US, Vietnam
https://receive-sms-free.net/ : 30+ Countries, 200+ Phone numbers
https://temp-sms.org/ : New Zealand only
https://freephonenum.com : US and Canada only
https://receive-sms.cc/ : India, US, Hong Kong, Russia, Canada, Philippines, Ukraine, Portugal, Netherlands, Kazakhstan, Georgia,
https://www.receivesms.co/ : USA, Austria, Australia, Belgium, Canada, Spain, UK, Italy, Poland, Puerto Rico, Portugal, Sweden
https://getfreesmsnumber.com/ : Belgium, Estonia, Canada, France, Poland, Sweden, UK, US
https://temporary-phone-number.com/ : US, China, Myanmar
https://receivesms.cc/ : US, UK, Ukraine, Netherlands, Czesh Republic, Poland, India, France, Hong Kong, Austria, Canada, Georgia, Croatia, Israel, Kazakhstan, Myanmar, Mexico, Serbia, Russian Federation, Sweden, Vietnam, SA