So we have been a bit lazy on this thinking things would eventually rectify and get better but no. 
Since the change was made from how the tapo bell connected with the iphone (to make it look like an incoming call) when bell pushed we can see camera hear sound but the party pushing the bell can never hear us. 

Previously when we installed the tapo bell the system worked very well with little or no issues. 

If I cancel the incoming call, go into the app and connect with the device we can see, hear and communicate by holding the button to talk, but only after canceling the incoming call and re-connecting through the app, often by the time we do all of that the person at the door has gone or is walking away.  
Is there a way of reverting back to how the tapo bell connected with the mobile phone originally?

Any assistance will be greatly received.