Missed call notification - ${calleridcontactname}

Hello,

I have a S20 PBX and a question about setting up "Missed call notifications".
Hope someone can point me in the right direction.
The emails are ariving just fine, but ${calleridcontactname} from the template is always empty.
For example, I have setup the extension 1 
I make an internal call to extension 2, but extension 2 does not pickup.
Now, extension 2 gets an email with the subject and body:"You Have a Missed Call from 1" 
What I would like is to also get the name associated with that extension.
As in: "You Have a Missed Call from John Doe / 1"
In the email template for missed calls, I can see: "The contact name matched with the caller ID (if any): ${calleridcontactname}" but how does one match the caller id with ${calleridcontactname} is unclear to me.
The full name of the person at extension 1 is being displayed on the phone of extesion 2.

Is there any trick to pass the actual "Caller ID Name" into the missed call notification?

I can see that I can modify the extension's Caller ID and that will show up in the email notification, but: 1. Caller Id cannot contain spaces or other signs and 2. On my IP phones, I will get the same name showing twice on the display on incoming call.

So I guess I just need to switch the value of "Caller ID" to "Caller ID Name" in the missed call notification template. The question is: how can I do that?

Thank you.