Wifi based office pbx using android phones and asterisk

Can I make a system where, WIFI connected android mobile phones and computers with asterisk installed, can communicate internally in an office environment, using wifi as network., kind of WIFI based PBX?

At present using EKIGA through LAN I can call to asterisk computer.

Is there a way I can call from Mobile phone using wifi only to asterisk computer? Which apt I should use?
Then finally is it possible using only wifi I can make a computer call a wifi connected mobile phone?

In fact question is finally establishing a voice communication in office environment using android phones, asterisk computer wifi connected, using WIFI.

Kindly advice