https://www.google.com/search?q=regexp+телефонный+номер
https://ru.stackoverflow.com/questions/107021/%D0%A8%D0%B0%D0%B1%D0%BB%D0%BE%D0%BD-%D0%B4%D0%BB%D1%8F-%D0%BD%D0%BE%D0%BC%D0%B5%D1%80%D0%B0-%D1%82%D0%B5%D0%BB%D0%B5%D1%84%D0%BE%D0%BD%D0%B0
Первый в выдаче