You absolutely can! In fact, a lot of contact centers use Blitzz exactly that way. They get a phone call through their IVR, then the friendly agent sends the customer a link via Blitzz and starts the video call. Instead of interrupting the audio call, the carry on without a care just using Blitzz for the video part maintaining a seamless experience and happy customers! In fact this is a trick that can be used with the customer has spotty internet, even if the video drops, you can tell the customer though the PSTN phone call (sorry that was tech speak, PSTN meaning the regular phone call) to perhaps walk closer to the router or an area with a better cellular connection to continue with the video call. Aren't we humans (and owls) clever?