---------+-------------------+---- (PSTN Line)
         |                   |
         |                   |       +-------------------+
         |                   +-----> |                   |
         +----> Phone 1              |  Sipura SPA-3000  | -----> Phone 2
                             +-----> |                   |
                             |       +-------------------+
                             |
-----------------------------+----- (LAN)





----------+-----... (PSTN Line)
          |
          |       +-------------------+
          +-----> |                   |
                  |  Sipura SPA-3000  | -----+---------+----...
          +-----> |                   |      |         |
          |       +-------------------+      |         |
          |                                  V         V
----------+-----... (LAN)                  Phone     Phone
                                            (1)       (2)