I am not fully familair with Samsung systems but after 2 or 3 visits I have managed to get everything working to the customer's satisfaction - with on exception:

when ext 213 is dialled, on answering that extension, four tones can be heard (1,2,3,4 I think)before the call is connected.

I haven't a clue what's causing this. Can anybody help please?

213x would be an analog extension?
Check mmc 207 VMAA PORT and check to see if 213 is in there.If it is remove it.

PVJ is right on! It is set up as port type VMAA. Just change it to normall in MMC 207.