[VoiceOps] Geographic redundancy

Alex Balashov abalashov at evaristesys.com
Wed Aug 12 03:03:09 EDT 2009

Kenny Sallee wrote:

> OK I see - from a CLEC perspective - is it a legal requirement to do 
> so?  I've read some of this tonight: 
> http://www.voip-info.org/wiki/view/How+to+start+a+Clec and although it's 
> mentioned a bit I'm not clear on if it's a legal requirement of a CLEC 
> (or just implied because in 1996 that's just the way it was)

First, that document is a bit simplistic and dated.  There's no such 
thing as a "pure-resale" CLEC any longer;  that's what UNE-P was, and it 
went away in 2003.  You can resell things from the ILEC (albeit, not 
especially profitably), but you still have to have facilities.  It is no 
longer possible to rent and resell ports on an ILEC switch.  There were 
a lot of arbitrage/resale plays that died when that ruling came down.

Otherwise, in your question, are you referring to SS7 interconnection 
with the incumbent?

I don't believe it's necessary to have any physical interconnection 
active in order to have a CLEC license and do nothing with it. 
Interconnection is just a practical requirement of operating as a CLEC; 
  it's part of the definition of a facilities-based CLEC that it 
connects to the ILEC, because the CLEC is entitled to take advantage of 
some of the ILEC's physical plant, network, and various other 
facilities.  CLECs lease copper services in order to build circuits to 
customers that the ILEC's plant can reach, to colocate in ILEC central 
offices, are eligible for certain types of special rates for access 
products, etc.

But even if you're not colocating in COs or generating UNE circuits, you 
still have to pass traffic to the ILEC because a majority of intra-LATA 
subscribers are going to be ILEC customers in your local rate center, or 
reachable via the ILEC's one or more tandem offices.  IXCs also 
traditionally land at the tandem, although it is possible to connect to 
some of them directly with access circuits or VoIP peering.  Other 
competitive carriers operating in the same LATA are also met at the ILEC 
tandem, and so on.  There are some alternatives to ILEC tandem access 
such as Neutral Tandem, but these aren't substitutes for the ILEC tandem 
- they just get you a cheaper way to meet the same players in your LATA 
and bypass some tandem access charges.

The other thing you have to keep in mind is regulatory obligations faced 
by CLECs.  For example, as a CLEC you're required to provide equal 
access to any IXC (long-distance/inter-LATA carrier) the customer wants 
to use via 1010 dial-around or PIC.  How are you going to allow them to 
use *any* CAC if you're only directly connected to two IXCs?  You can 
only hit up the rest at the Bell tandem.  Same for emergency calls: 
hitting PSAPs requires going through special 911 trunk groups on your 
SS7 IMT to special 911 tandems run by the ILEC.  Add number portability, 
directory services, number pooling, and a bunch of other good things, 
and, there's not really a way to participate without connecting to the 

So, yes, in practice, you have to interconnect with the ILEC if you are 
a competitive carrier, and SS7 is the only way to do that.  Using some 
ILEC facilities is part of what it means to be a competitive carrier. 
If you have a free and clear monopoly on a small town of a few thousand 
people in rural Minnesota, plant and all, that may be small-town telco, 
but that's not "competitive," as conceived by TRA96.

If you don't want to connect via physical SS7 link circuits, see my most 
about SIGTRAN.  But you still need physical TDM trunks for the bearer 
portion of the interconnect.  You can get away with having someone else 
convert those trunks into VoIP and do the signaling to the ILEC for you, 
but, someone's gotta do it.

> ITSP vs CLEC redundancy sounds like it's quite different then - if you 
> must have SS7 links. 

It is.  But, beyond the SS7 stuff, it can be remarkably similar 
depending on how "soft" and/or IP-oriented the core equipment in use is.

>  From an ITSP perspective - redundancy sounds like it comes down to IP 
> latency between signalling entities  and their capabilities, hardware, 
> and cash (like mentioned below).

Latency actually isn't that big of a deal unless you're talking halfway 
around the world.  It's reliability, really.

-- Alex

Alex Balashov
Evariste Systems
Web     : http://www.evaristesys.com/
Tel     : (+1) (678) 954-0670
Direct  : (+1) (678) 954-0671

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