I have deployed a couple of these for production and you do require the DNS SRV records (internal and external)
There must be an ExpresswayC and ExpresswayE deployed, you do need a proper certificate validation (your own cert auth or through provider) between the ExpresswayC and ExpresswayE SIP/TLS for MRA. No wild card certificates can be used.
Certificates between the ExpresswayC and the Call Manager, Presence, Unity Connections you don't need validation or you can use TCP (you can also just click accept from the Jabber Clients also)
Check out the session PDF on this link (right hand side) which is very good run down and configuration.
I would normally do firstname.lastname@example.org as users can relate to.
From my understanding effectively the Jabber client just uses the domain portion to find the SRV record for connection to the ExpresswayE server (or presence if internal) then presents the username portion only (without the domain) as LDAP sync would most likely have the SamAccountID.
Since traditionally users just enter their ID and don't care what the domain is, this can get complicated though say if the organisation email is different to their windows login could be their employee ID the user would have to ender employeeID@domain.com and not their email i.e. email@example.com. There are ways to deploy jabber to have a default domain lookup so users should just enter their ID only. Its really just a training thing.
I really apperciate your help, now i can't proceed in my lab with expressway as the administration guide shows the configuration for expressway C and E but i can't find a way how to make the server E or C
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.