See this FAQ:
I know a lot of people worry about not being able to use WhatsApp on the mudita pure, but I think with this new setting, there is no need for it anymore. You can use WhatsApp on your desktop, and enjoy being disconnected when you close your desktop 
WhatsApp was my number one reason for not being able to stop my severe phone addiction, I am super happy that I can not use WhatsApp as an excuse anymore to open my iPhone, and disrupt my sleep and quality of life.
It good but…
If you don’t use your phone for over 14 days, your linked devices will become disconnected.
So you can’t turn off your phone and throw it in a storage box. You have to open whatsapp on your phone at least once every 14 days. 
Well… still better than nothing. Beggars can’t be choosers.
This is actually a GREAT alternative. Thanks for sharing. every 14 days is just TWICE a month. I can agree to look at my old phone twice a month 
Since 2013 there is Viber desktop, for Viber addicts 
Will it be integrated for third party whatsapps like fmwhatsapp, gbwhatsapp etc.? These whatsapp mods are very much advance in features and have nothing worry about privacy.
Hi annamore!
I don’t really want to have a Whatsapp in any form on the Mudita Pure. While these particular mods may not have privacy concerns, they are a constant source of anxiety and distraction. So they represent exactly what I’m dying to avoid with the Mudita Pure.
Nevertheless, I am aware that not implementing group messaging is an exclusion criterion for many.
People that want feature phone with limited WhatsApp can try plenty of cheap KaiOS phones. Meudita is not made for social media, its ANTI social media phone
Mostly integrating API’s don’t allow a third party apps to be integrate with there services like Twilio, but this can be possible if the API’s developer will add this feature /option then this is possible to integrate these mod applications.