Enter a valid US mobile number

Short answer. Ringer accepts a US mobile number written as ten digits, or eleven digits starting with 1. Spaces, brackets and dashes are fine; a country code other than 1 is not. If you are outside the US, or you do not want texts, use the email option instead. Every feature works without a phone number.

Why it happens

Text messages are sent through a US texting program, so the number check is strict. The same rule appears in a few places with slightly different wording:

• "Enter a valid US mobile number." on "Join your game" (Continue with phone) and on the text updates opt-in page.
• "Enter a valid mobile number." when a Commissioner adds a player to a roster.
• "Add your mobile number to get text updates (or uncheck the box)." on an RSVP page when the text consent box is ticked but the number is blank.
• "That mobile number doesn't look right." on a league registration form.
• "Enter a valid phone number (or leave it blank)." when a Commissioner edits a roster phone.

What to do

1. Type the number as (555) 123-4567 or 5551234567 or 1 555 123 4567. Ringer strips the formatting. Do not include +44 or any other country code.
2. Check the number is a mobile, not a landline, and that it can receive texts.
3. On "Join your game", use the number your host has for you. "We'll text you a 6-digit code. Use the number you signed up with." If your host has your email instead, tap Use email instead and then Email me a link.
4. On an RSVP page the number is optional. Leave it blank and untick the text box if you do not want texts; you can still answer in, maybe or out.
5. Outside the US, ask your host to invite you by email. Sign-in by email link and every reminder by email work the same way.

Whether Ringer actually sends texts depends on your deployment and, for leagues, on the consent you gave at registration. See I'm not getting texts from Ringer.