Scenario: 2 office spaces within the same building (approx 50m apart), 8 workstations in office 1 and 6 workstations in office 2. Every workstation will have 2 network connections (1 for data, 1 for a phone).

The data network I am happy with - 1 switch in each office with a link between them, each workstation connects its local switch.

My question is can I achieve a similar dual star topology for the phone system ? i.e. one cat5 link cable between offices instead of having to run 6 separate cables from office 2 back to office 1 where the phone system will be located (pictured) ?

network map

If so, how would I implement it ? What hardware would be required ?

Thanks in advance

  • Some details about your make / model phone system are going to be helpful. If the phones aren't plugging into Ethernet but, rather, are plugging into "digital line cards" (or some such) in the phone system you're probably going to be stuck with a home-run from each phone back to the phone system. Jan 9, 2012 at 15:33
  • The phone system in a Panasonic KX-TDA15 which I believe is a hybrid IP/PBX system.
    – JimmyJ
    Jan 9, 2012 at 17:08
  • What model handsets are you using? It looks like you'd need the KX-TDA0470 (IP-EXT16) line card installed in the system to support IP telephones. Otherwise you're stuck using "digital" phones (which are not Ethernet / IP devices). Jan 9, 2012 at 17:18
  • The phone system is currently in basic form and only has 3 x KX-T7630 handsets connected to it. I will likely need to buy at least 8 more handsets (in addition to extension cards) to cope with the desired capacity so at this stage I could consider replacing parts if it meant that I could piggy back the data network?
    – JimmyJ
    Jan 9, 2012 at 17:36
  • 1
    I think you'd do well to talk to the vendor you got the phone system from about integrating the phones with the data network. Sounds like you're in a position to buy some hardware and make that happen. Jan 9, 2012 at 18:26

2 Answers 2


You can always have multiple PBXs, in roughly the same place as the switch on the data network. Probably one of them would be a "slave" (or similar terminology) depending upon the exact scenario and kit supplier.

This is all pretty obsolete though - I'm not aware of any new phone systems that have been installed that aren't IP based for some time now. The network of your IP based phone system can be shared with the data network, or configured in parallel, with the topology of your choosing, just like any other data network.

  • 1
    There are plenty of non-IP phone systems getting installed every day. They may be "obsolete", but there is still some favorable pricing for small installations to stick with "traditional" key phone / PBX offerings. Jan 9, 2012 at 15:34

The simple answer is yes and you implement it the same as you have done for your PC network with 2 network switches, one in each office connected together over a cable that runs between them

Then just hook your phone system also into one of the switches

Of course all this assumes your phone system is IP based.

  • That's a pretty big assumption. Jan 9, 2012 at 15:35
  • He did say it was a "Digital" system :-)
    – Phil
    Jan 9, 2012 at 15:59
  • 2
    Typically "digital" in reference to telephone systems means proprietary digital communication between a "line card" and a handset (sometimes a proprietary variant of ISDN). It's was a more common marketing buzzword used in the 90's to imply a richer feature-set at the handset and better audio quality than analog systems. It usually doesn't mean IP. Jan 9, 2012 at 16:09

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