You get stuck in signup with the error message "The phone number must be a non-empty E.164 standard compliant identifier string".
E.164 is the international telephone numbering plan that ensures each device on the PSTN has globally unique number. This is what allows phone calls and text messages can be correctly routed to individual phones in different countries. E.164 numbers are formatted [+] [country code] [subscriber number including area code] and can have a maximum of fifteen digits.
Examples of E.164 Numbers
+14155552671 (Country Code: 1, Country: US, Number: 4155552671)
+442071838750 (Country Code: 44, Country: GB, Number: 2071838750)
+551155256325 (Country Code: 55, Country: BR, Number: 1155256325)
- Go back and enter your phone number in an E.164 compliant format.