Just subscribed Poivy
poivY, and added in Voxalot. When dial to use PoivY the voxalot either give busy tone or message try again. Although to make outbound call you do not need to register, but I successfully registered to check that Poivy proxy
sip.poivy.com is working. Still it did not help and same busy tone.
To further explorer whether Poivy has compatibility issue with Voxalot, I used with Easypabx and was I able to make calls without any problem.