Learn English – You can still contact me “through” your phone vs. “via” your phone

The usual way of asking for assistance over the phone is

Could I speak to someone in accounts please.
I'd like to speak to someone in accounts please.
Accounts please.
I have a question about my account.

Being put through on a call is hold over from the days when there were central operators whom one had to speak to to make a connection, but the phrase can still be used today.

The lines were so busy, but finally I was able to get through to customer service.
The lines were so busy, but finally I was able to get someone in customer service.

The caller is not the one putting through the connection, but is the one who gets the connection.

Such a person is often called a "point of contact". If you want to emphasize that this POC is only for external relations, then I can't think of a better way of saying that except explicitly, e.g.:

He/she is our point of contact for external (or in this case perhaps "interdepartmental") relations.