[Asterisk-Users] Softswitch

[Darren Martz]

Thanks Brian, and thanks again for the included definitions <grin> - that
helped too. Your comments are really helping clear many questions.

I suppose our intensions are to become an IXC.

So if my local carrier is sporting old technology, they'll provide TDM
services. So if I understood you correctly, the "in-band signaling" is
typically SS7, and the alternative is typically PRI? Sounds like one carrier
more of the call management tasks and the other is a more finished product -
and you pay more for each PRI channel right?

I know our local carrier recently upgraded the entire LD infrustructure to a
Nortel VOIP solution (Telus in Canada). Perhaps they could provide VOIP
channels as you indicated instead of TDM services. FYI: Telus spans across
the entire Canada, and are a major carrier. They are also a major pain to
deal with, and I'm not sure they'd be willing to sell a VOIP package.

Hmmm.... if our target is to manage a maximum of 2000 concurrent calls (for
arguement sake), I suppose a softswitch is overkill. Although I did notice
that companies like MetaSwitch operate as small as 400 lines.

So if our only option was a TDM based solution, and we used Asterisk as our
"softswitch", what signaling would be ideal to keep the cost at a minimum? I
don't recall Asterisk supporting SS7. Besides I read the Telco's only allow
SS7 products they have tested and certified.

I wonder what would happen if the carrier provided VOIP channels. I suppose
it would still use T1s, but with what form of signaling?

Cheers,
Darren

> Subject: Re: [Asterisk-Users] Softswitch
> From: Brian D Heaton <bdheaton at c4i2.com>
> To: asterisk-users at lists.digium.com
> Organization: bdheaton at c4i2.com
> Date: Fri, 07 Nov 2003 21:26:49 -0500
> Reply-To: asterisk-users at lists.digium.com
>
> Darren,
>
> The answer (unfortunately) is "sort of" and "it depends"
>
> ----- Definitions -----
> LEC = Local Exchange Carrier
> CLEC = Competitive LEC
> IXC = Interexchange Carrier (LD company)
> -----------------------
>
>
> In most cases a traditional phone company is going to want to hand off
> TDM (circuit switched) services to you.  This is true whether you are a
> normal business or a CLEC/IXC.  If you are a CLEC with SS7 connectivity
> (and an assigned point code) they will hand off T1s and do the
> signalling out of band over the SS7 connections.  In-band signalling is
> possible, but not common anymore. I know that in the late-90s in
> SouthWestern Bell land they often wanted to hand off calls from their
> 1AESS switches in MF format rather than SS7.
>
> A typical business would be handed either in-band signalled T1s or
> PRIs.  I don't know of any cases where private enterprises have gotten
> their own point codes and SS7 connectivity, but someone else may have an
> example.
>
> In the market now are firms which offer the end-user individual or
> business VoIP origination/termination of both local and LD calls.  While
> the customer of these firms sees a VoIP interface I would bet that the
> hand-off to the terminating LEC is still done via TDM circuits.  This
> may change in the future as the IXCs complete their transitions to VoIP
> internal trunking networks.  I don't expect the LECs to change rapidly
> though.  Their cost-recovery and depreciation models are based on their
> switches lasting a loooooooong time.  If anyone has an example of a
> traditional US LEC offering VoIP hand-off and termination I'd love to
> hear about it.  I just haven't heard of a real-world example yet.
>
> Depending on the size of the deployment, a softswitch may be the way to
> go for hand-off to a LEC.  Given the size of typical carrier grade
> softswitches though, I'd think that is something you'd only be looking
> at if you were a very large enterprise or some type of carrier.  The
> size of the enterprise and the mix of traffic would determine where the
> crossover is between a softswitch and another solution.  Actually, you
> could make a case that * is a softswitch.  Really you're just talking
> about scale here.
>
> The big question is when does a * server run out of gas? If you have 4
> quad-PRI boards in a system you can provision 368 trunks via PRIs.
> Depending on the average length of call that is quite a bit of
> trunking.  I've seen CLEC trunk-groups to the access tandem that were
> smaller than that.
>
> Hopefully this answers some of your questions.....
>
> THX/BDH
>
>