Guides
How to check if a phone number uses iMessage
What iMessage registration means, blue vs green bubbles, iMessage vs RCS on iPhone, what businesses can and can't send, and a bulk API example.
7 min read
Articles tagged “Channel selection”
7 articles.
Developers
How to check if a phone number is on WhatsApp with an API
How a WhatsApp registration check works, what registered, not registered and unknown mean, and how to call it responsibly from cURL, Node and Python.
8 min read
Deliverability
How to choose a messaging channel by country
WhatsApp, Telegram, Viber, LINE, Zalo, RCS or SMS? How to pick a channel per country for messages customers expect, and measure it on your own base.
6 min read
Guides
Messaging-app registration checks: a guide for every app
What a registration check tells you for WhatsApp, Telegram, Viber, Signal, iMessage, RCS, LINE, Zalo and more: modes, unknowns, billing and consent.
8 min read
Deliverability
RCS capability check: what it tells senders before they send
What an RCS capability check tells you before sending, iPhone support, RCS vs SMS fallback, what RBM is, and a decision table with bulk API examples.
7 min read
Guides
Telegram number check: a practical guide to what it can and can't tell you
How Telegram's phone and username model differs, what a registration check can and can't tell you, how privacy settings affect it, with API examples.
7 min read
Deliverability
WhatsApp OTP vs SMS OTP: cost per verified user, with a calculator
WhatsApp authentication rates vs SMS prices by country, the October 2026 changes, and a calculator for cost per verified user including SMS fallback.
7 min read
