Develop and design chat app ios and android

General information for the business: Developing mobile chat app
Kind of development: New program from scratch
Description of requirements/functionality: I have an example of the type of app I want to build. There will be alot of backend work involved to make sure the database captures the appropriate data from users. Database needs to be useful and capture certain information that will be relevant for business purposes
Specific technologies required: ios, android, mobile app development, mobile app design,
Extra notes:

Would like to include the ability to invite people/friends via text message and mobile phone book as well