[asterisk-users] Phone system layout suggestions

[Paul Hales]

Bill Andersen wrote:
> I am thinking about a change to our company's phone "layout" and would like
> to get comments from people who have done something similar.
>
> Currently, we have 3 locations - each with their own Asterisk PBX.  The
> corporate office has a PRI.  Each remote location has a SIP provider for
> 5 channels of SIP going to their own PBX.  Interoffice calls use the PSTN.
> Most inbound calls come to the headquarters via a toll free number.
>
> We are adding another remote office and are planning a MPLS network to
> connect all locations for DATA.  As we really want a "centralized"
> switchboard
> anyway, I thought with QoS and an MPLS, I could eliminate the remote PBXs
> (and not have to buy another for the new locations) by simply using the MPLS
> to
> tie everything together.  See below.
>
> /--------------------\
> |  CORP HEADQUARTERS |----> PRI (23 Channels, 100 DIDs)
> |  Asterisk PBX      |
> |  30 Polycom 501s   |
> \--------------------/
>           |
>           | < 3Mbps MPLS (2 T1s)
>           |
> /--------------------\
> |  MPLS "Cloud"      |
> \--------------------/
>   |       |       |
>   |       |       \---SIP over MPLS 1.5Mbps T1---Branch Office 1  (5 Polycom
> 501s)
>   |       |
>   |       \-----------SIP over MPLS 1.5Mbps T1---Branch Office 2  (5 Polycom
> 501s)
>   |
>   \-------------------SIP over MPLS 1.5Mpbs T1---Branch Office 3  (3 Polycom
> 501s)
>
>
> Question 1: I've never had an MPLS network with QoS.  Will the call quality
>             "Really" be as good as AT&T assures me it will be with QoS?
> Assuming
>             we never have more than 5 calls going over the MPS from a
> branch?
>
> Question 2: MPLS are pretty reliable, but last mile connections can be cut,
> hardware
>             can fail at AT&T or whatever.  Is this putting too many eggs in
> one
>             basket?  If I lose the headquarters T1s (MPLS or PRI), everyone
> is
>             down.  Would "You" do it this way?
>
> Question 3: (OT) For those who have used an MPLS.  How much better
> throughput for
>             DATA (NOT VoIP) should I see compared to using the Internet?
> I'm mostly
>             just curious here and realize it is hard to compare, but when I
> do any
>             type of file transfer between office right now, I use FTP over
> the Internet
>             and both ends have a T1.  Assuming an MPLS on each end, what is
> your
>             experience when comparing average "throughput" compared to an
> Internet
>             transfer.  Just a guess of what you've seen.  (i.e. Yes, you'll
> see
>             a big difference, maybe a little better or couldn't really see
> that
>             big of a difference)
>
> Thanks for your input.
>
> Bill
>
>
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One of the techs I know built such a setup for a company in australia - 
it actually became one of the original Asterisk case studies.
She had about 200 phones over 70 sites (with between 2 and 5 phones per 
site) - all over an MPLS network.

Her only comments - get decent phones (she used polycoms), use g729.

PaulH