With WhatsApp you already cover probably 90% of Latin America and Europe; Telegram would be really nice to have since it's gaining traction and it's popular among tech-savvy users.

Russia and Asia probably use other apps like WeChat, honestly no idea.

> Noted. FWIW SMS is not a requirement to use /tap. And I would love to build more messaging integrations. email me with suggestions!

LINE messenger in Southeast Asia KakaoTalk in South Korea

Telegram not would also do the job.

Whatsapp has a business API pretty much exactly for stuff like this.