After all, the best messaging app in most countries or continents is the one most other people are already using there.

e present a protocol for secure online com-munication, called “off-the-record messaging”, which hasproperties better-suited for casual conversation than do sys-tems like PGP or S/MIME.

Use the search field at the top left side of the app and enter the email address or phone number of the person you want to call.