Rather than email support, ask them to call you and take remote support. That way, they're more willing to provide firmware upgrade. I kept mailing them and they told me that i was on the most current version. But once on remote, the person concerned provided me with the latest.
Check to see if the update resolves it. I would also suggest you do a factory reset after the update.
But what is weird in your case is that usually MicroSIP works fine, and zoiper is the trouble giver.
