It is called a "short code" in the telecommunications industry and it is basically a special phone number used specifically for text messaging. Using short codes works the same as texting a regular 10-digit phone number. Short codes are only available in the U.S. and Canada.
The short codes available are:
- 22333 For the US
- 37606 For the US and Canada
We do have a 10-digit number available if needed (in the U.S. this is only available on paid plans). You can view the other available numbers on your settings page, under International Text Messaging.