Click to call zoiper doesn't dial the number

Question

I have set zoiper as the default app to open callto:// and tel:// protocol and i have set the integration options in zoiper to (catch the 'callto' protocol requests from url).

I get a pop up to allow to open zoiper but then it doesn't dial the number

 What's the problem?

Comments

Can you tell us which Zoiper you are using, is it Pro or Free, on which operating system an with which browser ?