Customer is asking for a similar feature in RC for Zendesk, that's currently available in RC for Salesforce. Being able to dial via browser and not having the RC App pop up to make the call. See Screen Shot from RC for Salesforce. You have 4 options available from within the calling option of the addon, whereas in Zendesk you only have 3. If customer is mainly in Zendesk app, they still need to toggle between RC App and Zendesk for it to work, this can get a little confusing for them if they are using a single screen. Its just not as user friendly as RC for Salesforce