UniVoIP App uses your contacts saved on your phone. UniVoIP App's contacts are continually synchronized with your native contacts; adding, modifying or deleting a contact from one list updates the other list.
You can make a UniVoIP App call so long as you're not already on a native call or not already on two UniVoIP App calls. You can make a native call, regardless of the state of UniVoIP App.
An incoming UniVoIP App call rings on your phone unless you are on a native call or you are already on two
UniVoIP App calls.
Incoming native calls: Being on a UniVoIP App call has no impact on your native phone: native calls will be received in the usual way. Therefore, you should be prepared to accept or decline a native call.
If you accept an incoming native call, any live UniVoIP App call goes on hold. You won't be able to take the UniVoIP App call off hold until you end the native call. You can have up to two UniVoIP App calls established at the same time and switch between them.