Hello,
I have seen and understood the project requirement as i have already done working with C Programming, VoIP and Asterisk PBX. We have a team of skilled designers and professional application developers (Android and iOs) who have a vast expertise and have already made hundreds of apps competing on Play stores. We have a group of expert App Engineers, UI UX creator and experienced, they made few sorts of Apps dependent on Android Studio, Flutter, Firebase, Swift, Kotlin. To approximately know about them you can have a look on portfolio on my profile. Kindly lock in chat with us and tell us a briefing about your thought that you have in your mind.
Thank you have a good day!