CODE EXAMPLE FOR JAVASCRIPT

regex for international phone number

+(9[976]d|8[987530]d|6[987]d|5[90]d|42d|3[875]d|
2[98654321]d|9[8543210]|8[6421]|6[6543210]|5[87654321]|
4[987654310]|3[9643210]|2[70]|7|1)
W*dW*dW*dW*dW*dW*dW*dW*dW*(d{1,2})$
allows for valid international prefixes