I just installed Signal on our cell phone.
https://signal.org/
Open Source, total encryption and highly recommended by none other than Edward Snowden.
Started as text app but does voice now too.
Signal isn’t really relevant to the Chrysaor attack/infection.
Signal will encrypt end to end calls and text (if keys are properly verified) but doesn’t protect your phone against spyware. Two different things.
In fact, if your phone was infected with Chrysaor, your phone and text messages could conceivably be intercepted BEFORE they were transmitted securely using Signal or AFTER you received and decoded them.