[asterisk-users] VOIP with PSTN backup

[Peter Lindquist]

Brian,

Take a look at www.intertex.se I believe they have what you are looking for.

Peter

Brian Candler wrote:
> I'm looking for a way to set up a VOIP network in branch offices where one
> or more phones have "lifeline" capability, i.e. can place calls if the IP
> network or VOIP service dies, or even if power goes down. (I'm thinking of
> business continuity here, not just emergency services)
>
> This seems to limit my choice of products somewhat, and I was wondering if
> anyone had recommendations for use in this scenario.
>
> The approaches I'm thinking of are:
>
> (1) Use an ATA with PSTN passthrough or FXO port, and connect an old
> analogue telephone to the FXS port.
>
> In this case, the analogue phone has lifeline. If there's a true FXO port
> then PSTN calls can in principle be routed to/from other VOIP phones in the
> office (but see below)
>
> There seem to be a few to choose from, although far fewer with a true FXO
> port.
>
> (2) Find a VOIP phone with integrated PSTN or FXO port
>
> In this case, the only one I have found so far by searching the web is
> Clipcomm CP101.
>
> I have also read that many FXO devices tend to be badly implemented; in
> particular, on seeing ringing voltage, they actually pick up and answer the
> call, instead of sending off a SIP INVITE and waiting for the OK before
> connecting. I'd certainly like the device to behave properly in this regard.
>
> As a second part of this question, it would be extremely desirable if the
> backup PSTN service were available to all the phones in the office. That
> means:
>
> (a) incoming PSTN calls could ring *all* the VOIP phones in the office, not
> just the one phone or ATA connected to the PSTN line; and
>
> (b) any VOIP phone could route a call out over the LAN to the local FXO PSTN
> port, e.g. by dialling a prefix to access it.
>
> This isn't so essential but it's definitely desirable. Any recommendations
> for how to do this too?
>
> A large number of offices is going to be involved, and I want to keep as
> much switching "intelligence" centralised as possible, both for ease of
> management and to keep the cost down. That is, I don't want to install a
> PC + TMD400P + Asterisk in each location, but just a small media gateway or
> VOIP phone.
>
> However I can see that the incoming ringing issue will require call forking,
> so I am happy to install an OpenWrt box running Asterisk or siproxd or
> whatever in each site. Being diskless and low power should mean little
> maintenance is required. But such a box isn't going to be able to take an
> FXS/FXO card, so I'll still rely on an ATA or VOIP phone to present a PSTN
> interface. So that's the key part I'm looking for.
>
> Finally, the devices must be robust (i.e. not need power cycling every 24
> hours) and centrally manageable.
>
> I think that's about it - many thanks for your ideas and experience!
>
> Cheers,
>
> Brian.
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