Do you have to register your sender name per country?
More and more countries require an alphanumeric sender to be registered in advance. Without registration your message is refused or delivered from an unknown number.
Why those rules exist
To stop somebody sending messages under the name of a bank or a government service. The downside is paperwork for legitimate senders.
What is usually asked
Proof that the name belongs to your organisation: an extract, a trademark registration, or a declaration. And an example of the kind of message you send.
Allow for lead time
This takes days to weeks depending on the country. Plan it well ahead of a campaign — not the week before.
What happens without registration
It varies per country: refused, or your name is replaced by a number. That second case is treacherous, because your report says delivered while the recipient has no idea who it is from.
In practice
For every new destination, state which sender you want to use and ask what applies there, before you plan volume.