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I need to install 5 telephones in our new offices, however, we have very limited bandwidth so I don't think a VOIP provider will be a realistic option. I have had two standard land lines installed for the time being.

Is it possible set up an internal VOIP system that can run 5 phones (and 5 simultaneous calls) over the two standard phone lines, using a IP PBX or something?

I'm a VOIP noob so please be gentile!

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Are you saying that you have two ANALOG pstn handoffs? As in, two phone lines? If so, then NO, its not possible to run 5 phone calls off of two lines. –  SpacemanSpiff Apr 30 '12 at 16:05
Oh and define "limited bandwidth". DSL? 56k? Cable modem? –  SpacemanSpiff Apr 30 '12 at 16:08
Like Spaceman said. You can use an IP PBX and IP Phones but the PBX will need to have 5 PSTN lines setup with the phone company as a trunked group if you want 5 calls at once (inbound/outbound added together), unless you want each person to have their own phone line, in which case you can forgo the PBX altogether and just run the lines to each phone, :). Just call your local telco and they'll quote you what you need with various options. –  TheCleaner Apr 30 '12 at 16:11
In agreement with the above comments. Just thought I would note even with limited bandwidth, if your router supports QoS or traffic shaping you still may be able to achieve satisfactory results. –  Robin Gill Apr 30 '12 at 18:16
The bandwidth (shared between 6 users) is 2.5mbps down and 0.6mbps up. Is anywhere near enough? 5 simultaneous calls is worst case scenario, up to 3 is probably more likely. –  Fly_Trap May 1 '12 at 8:40

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