Intercom several phones at one time

[Dataworks]

Good day, we have a situation where we have an epygi M8L with 8 snom 320 phones that are configured within a paging group. User press a function key that dials the extension and then user makes a general annoucement. Customer would like the paging group to work like an intercom where the customer could establish a two-way conversation. For example:
"Joe" who is at extension 101, is looking to talk to "Jim" who is not at his desk. Joe presses function key 1 which is programed to speed dial the paging group. Joe makes his annoucement which is heard through every phone. Jim would like to pickup the nearest handset while Joe is still on and be able to communicate with Joe.

I don't see how this is possible; however it is a feature that the customer claims existed in their old analog system. Any suggestions?

We have programed speed dials to each extension and suggested that Joe's annoucement should be for Jim to call him at Ext 101, but they don't like this suggestion