Currently there are many ways to send a message to a friend. I listed nine different ways but only by cheating a little, as you will see in a moment. The cheat, by the way, LOWERS the number of ways, not raising it.
Landline
Cellphone
Email
Text
Visit
Visit a neighbor
Facebook
Other social media
US mail
The cheat is #8, since LinkedIn, TicToc, etc. are more than just one. Here's a list by monthly active users:
*Number of monthly active users worldwide updated October 2023.
But if the desired recipient doesn't use your chosen method, he might never know you sent a message.