VoIP calls are calls placed to contacts or other people using popular instant messenger programs such as Skype, Viber and Whatsapp. They are essentially the same as a normal phone call. The call is just being routed over the internet instead using the instant messenger program.
With FlexiSPY Extreme for iPhone, if the iPhone user uses either Skype, Viber or Whatsapp to make or receive calls then these calls will be automatically recorded and uploaded to your web portal for you to listen to or to download later for offline listening. This is VoIP call recording.
If someone you know is using an iPhone/Android and likes to use applications such as Skype, Viber or Whatsapp to make calls then you need FlexiSPY so that you can record those calls and find out what they are really up to. All call recording files are small in size for easy and convenient downloading so that you can listen to them on your PC whenever you want.