Looks like not only my sip phones have issues with pbxes...
E164 hasn't got a route as well??
Wasn't able to test your route, your system returned the following information: 0|Error 404 - An attempt to verify your SIP address was rejected because the user doesn't exist or the domain is invalid
I tried both <accountname>@pbxes.org
and <accountname>-<extensionnr>@pbxes.org