Can I send to a landline or abroad?

A landline doesn't receive an SMS the same way a mobile does; the gateway doesn't convert the message into a voice call. These lines are therefore ruled out.

For international, the routes, formats and rules differ from one country to another, with variable routing costs. Staying within the national scope guarantees a free, reliable and predictable send.

The format check on the form side refuses a non-compliant number outright, which saves you from believing a message has gone out when it wouldn't have succeeded.