My son-in-law also suggested Signal. It is peer-to-peer and is encrypted. I downloaded both last night.
I also have Signal but found out a Twitter IT Security agent helped start it up. Now it’s said to be monitored by Twitter.
It didn’t help to see Dorsey endorse it.
Twitter CEO Jack Dorsey says download Signal as US protests gain steam
On my Samasung Tab A tablet signal is not even listed in google play store. Might not be compatible? Anyone know why? I did download it on my phone.