@mailpravink there might be easy way to do it (like in some way e.preventDefault()), so you could try listening for some focus-like events, but since the behaviour may be somwhat platform dependent (I remember there being some platform inconsistencies) it may not work out of the box. I could be wrong but you could still try that. If it works then everything is perfect.
A somewhat related topic can also be found here.
So maybe there are plugins which may help, otherwise a hacky way would be trying to focus it again, but it may not work very well either.
And a final option would be thinking if you really need the feature - I think skype and most other chat apps do hide their keyboard when the user focuses out. On some phones the keyboard takes almost the whole screen (especially in landscape), so you should probably still give the user at least some way to hide it imo.
Sorry if my answer wasn’t very helpful. I hope you find a solution - if you do feel free to share it here again :) Good luck! ;)