I have 1 year subscribtion for your PUSH service. Initially it was working fine but since December it is very unreliable and actually doesn't serve its purpose. I experience 2 main problems:
1. Very often getting "failed registration" b/c Error 503(route not found) or 408(timeout)
2. Sometimes the phone shows the account is registered but actually it isn't on the SIP server.
Not sure what is the problems...maybe too small capacity and many customers or just bad design and support...for sure the problem isnt in SIP provider or the phone settings. Anyway, please take care to support properly the PUSH service ...otherwise it is just money grabbing non-sense.