Pretty much all the messaging app you can download on the Google Playstore can work. They only downside would be video calls as the P-one is meant to be dumb phone and has no front-facing camera.
Here's a short videoclip of apps being installed and ran:
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4355127/837053_383386.jpeg)
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4355127/563637_313774.png)
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/4355127/865556_1750.jpeg)