Sign up

Vonage Forum Menu

Vonage Forums
Vonage VoIP Forum
allommaCem Posted:
thank a lot for
your internet site
it helps a whole

In The Forum:
Im glad I finally registered
On Nov 10, 2015 at 12:33:23

sv777 Posted:
I have VDV21-VD
and I have a
question regarding
the green ethernet
light on the

In The Forum:
Vonage adapter green Ethernet blinking continuously
On Oct 31, 2015 at 11:44:24

egyptneyes Posted:
That sucks! Please
do let me know if
you ever resolve
this problem. On
another note,

In The Forum:
Recent calling problem from Egypt
On Oct 18, 2015 at 11:12:28

Rafik Posted:
I had the same
problems 2 weeks
ago .. you will
have to "Unbind
the port 5060

In The Forum:
Vonage device drops off network, cannot reconnect
On Oct 18, 2015 at 10:15:35

Rafik Posted:
I have only solved
the "connection to
the Vonage
network" problem
.. by bypassing

In The Forum:
Recent calling problem from Egypt
On Oct 18, 2015 at 10:02:03

egyptneyes Posted:
hi rafik I just
read your post
& I too am
having problems.
I was told that

In The Forum:
Recent calling problem from Egypt
On Oct 17, 2015 at 23:10:06

Rafik Posted:
Hello everyone ..
I'm a new
subscriber to this
lovely forum but I
have been a Vonage

In The Forum:
Recent calling problem from Egypt
On Oct 14, 2015 at 03:35:58

dconnor Posted:
It will ring on
their a few times
then go to
voicemail, they
will not know they

In The Forum:
Call Blocking
On Oct 05, 2015 at 16:30:26

lusitano Posted:
If I block a
number using call
blocking, what
will a caller hear
when he/she calls

In The Forum:
Call Blocking
On Oct 01, 2015 at 21:15:00

Lp2 Posted:
router. Get one
that allows you to
turn off SIP
ALG Google that

In The Forum:
VOIP call disconnecting home internet in 30Sec- Pls Help
On Sep 21, 2015 at 16:51:48

Vonage VoIP Forums

Vonage In The News
Vonage Holdings Corp. Reports Fourth Quarter and Full Year 2013 Results

Carolyn Katz Elected to Board of Directors of Vonage Holdings Corp.


Vonage Customer Reviews
Vonage vs. Time Warner Cable SoCal
Vonage vs. Time Warner Cable SoCal

Vonage UK Review
Vonage UK Review

Vonage Pros and Cons for 2006
Vonage Pros and Cons for 2006

Vonage, a VT2142 and a RTP300, My Experiences - A Detailed Review
Vonage, a VT2142 and a RTP300, My Experiences - A Detailed Review

Salt Lake City: impressions after several months
Salt Lake City: impressions after several months

Vonage Reviews

You Make The Call: SIP, NCS And How They’re Different

Vonage In Print News

March 8, 2004

By Leslie Ellis

Last time, we examined why SIP, or Session Initiation Protocol, is the kind of new thing that this industry ignores at its own risk.

This time, we’ll dive into how a SIP-based call is different than an NCS-based call — where “NCS” is shorthand for network-based call signaling, the method predominantly used by the industry’s PacketCable 1.0 specification. (That means it’s the spec most MSOs plan to deploy and most voice-over-Internet protocol telephony vendors are building their gear around.)

Before we even get started, know that both SIP and NCS take a gigantic leap from traditional telephony.

Oversimplified, that black phone bolted to the kitchen wall when you were a kid worked off the voltage of the actual phone line. Voip phones work by sending a series of electronic messages that emulate how the old black phone worked.

The chief difference between SIP calls and NCS calls is this: One (NCS) gets real chatty with the center of the network, to figure out what to do. The other (SIP) doesn’t —its devices get chatty with each other to determine their to-do lists. They treat the network as a go-between.

Both work to call or receive calls from that old black phone.

Packetcable Calls

As NCS is the method to be deployed by the MSOs doing VoIP, let’s start with that.

In the PacketCable world, you plug your phone into one of two devices. There’s an “S-MTA,” for “standalone multimedia terminal adapter,” or there’s an “E-MTA,” for “embedded multimedia terminal adapter.”

S-MTAs are like Voip sidecars. They plug into the Ethernet jack of a cable modem. E-MTAs are both a cable modem and an MTA, in one box.

Economically, sidecar S-MTAs are cheaper than E-MTAs, but E-MTAs are cheaper than buying a cable modem and an S-MTA.

Without batteries, E-MTAs go for $70 to $80, technologists say. That’s about $30 to $40 in incremental revenue compared to today’s volume-priced cable modems.

For this discussion, we’ll assume we’re dealing with an E-MTA.

When you turn it on, it gets two IP addresses: One for the cable modem, one for the voice activities of the MTA. The voice section also gets the electronic address of whatever softswitch is being used by that system.

Then, the chatting begins. The MTA pings: “Yoo hoo! I’m new here. Anybody there?”

The softswitch (which also goes by “call-management server,” or “CMS”) acknowledges: “I see you. Who are you?”

The MTA says what it knows about itself: “I’m a 2-line E-MTA.”

The softswitch gives it an identifying number and asks to be notified if anything happens. It’s specific about what could happen, like someone picking up the handset of the phone or dialing digits.

Your (NCS) Call

So that’s you, picking up the phone. Say you’re calling your childhood home, where that old black phone is still bolted to the wall, and your parents still have the phone number they had when you lived there.

(That last part doesn’t matter to this discussion, except that in these times, it’s oddly nostalgic to know anyone who’s had the same phone number for more than 10 years.)

The softswitch collects the dialed digits, and places the call — either linking to the public switched-telephone network over a “media gateway,” or finding the destination E-MTA.

In the latter case, a similarly lengthy dialogue happens with the destination E-MTA, to receive the call.

When the call ends, the E-MTA tells the softswitch that you and Mom hung up.

Again, this is an oversimplification. Lots of other things happen throughout the call, especially in setting it up and tearing it down. The point is that the activities are tightly managed by the softswitch.

In fact, the E-MTA is too dumb to know much beyond how to notify the softswitch when anything happens.

In the world of SIP, just the opposite is true. SIP devices, which are known in the lingo as “user agents,” or “UAs,” treat their work like any other Internet communications program. Destination phone numbers become much like e-mail addresses, for example, that can be dialed from a handset, a PDA, a PC or a laptop. Functionally, UAs are like a combination of an E-MTA and a softswitch.

Your (SIP) Call

Again, you decide to make a call. You could call Mom again, but the interesting stuff about SIP surfaces when you call another SIP device.

Example: You’re in Europe, Asia or anywhere else that’s not North America. You plug your SIP-equipped laptop into a broadband connection. You plug a headset into your laptop. You click on the phone number of your co-worker, Jane — a local call, even though you’re far, far away — and pay next to nothing, or at least less than the hotel would charge.

Notice I didn’t say “you pick up the phone.” You could pick up a SIP phone, but one aspect that’s different and interesting about SIP is the flexibility it offers, in terms of user interface — for you and for Jane.

For one, you’re not solely dealing with a 12-digit phone keypad anymore. To reach Jane, you could click on her e-mail address. The SIP agent within your laptop will look up all the different ways she can be reached (or not).

Similarly, Jane — who might think she was a better candidate than you for the overseas trip — can decide whether or not she wants to take your call. She can also pick how she wants to take it – on her PC, office line, cell phone, and so on.

Logistically, here’s (loosely) what happens: The E-MTA inside your laptop (and Jane’s) is pre-registered with a “registrar” (potentially offered by your cable provider), which keeps a database of SIP device addresses.

Jane’s might be “”

Like a routing database, the registrar exists to know who you are, so it can find you when you get a call, or route you when you’re making a call.

Invite Issued

Meanwhile, across the ocean, you click to dial. In the background, your SIP device is issuing an “invite” request to a location server, asking it to find Jane and invite her to the call.

Maybe Jane uses SIP on her PC and her phone. Your registrar passes your request to a location server, which doesn’t find Jane, so it passes the dialed digits to a redirect server, which locates her.

Back at the office, Jane sees your incoming call pop up on her computer screen. She answers — by donning a headset and clicking an icon on her PC.

In the background, Jane’s SIP device and your SIP device already negotiated an assortment of details about the call itself.

One example (of several) is which “codec” to use. “Codec” is tech-speak for “coder-decoder,” which is the thing that digitizes and squishes your voices for the ride over the wires.

Another example of the behind-the-scenes negotiations between your and Jane’s SIP devices is which port to use to establish the session for the two of you to talk. There’s back-and-forth chatting going on, but it’s happening directly between the two intelligent end points — not with the network.

The point: Contrary to NCS, SIP devices don’t need to ask the network what to do when you initiate a call, dial digits, talk and hang up. All they need is somebody to help route you to Jane.

Relative Merits

There’s no easy way to say whether NCS or SIP is “better.” Aficionados of both techniques generalize it this way: NCS is sturdy, but not amenable to quick changes. It’s a little better at regulatory stuff, like enhanced 911 and CALEA (the Communications Assistance for Law Enforcement Act of 1994), the law-enforcement part.

NCS also contains specific methods of offering quality-of-service guarantees, which matter in terms of offering sustainably good quality. This will matter big-time, especially as video telephony enters the scene.

SIP is more agile and is riding a big innovation wave right now. Plus, it’s not just for voice — instant messaging and video telephony work with SIP, too. But SIP is potentially more prone to integration hassles. Already, a data-communications trade magazine ran a front-page story last month about SIP incompatibilities with the firewalls that reside in people’s home networks.

Note that early adopters are already making SIP calls, but they’re doing so via competitive providers like Vonage Holdings Corp. — and, shortly, AT&T Corp., Verizon Communications Inc. and others. It just seems too logical and economical to assume that SIP won’t spread like wildfire.

Vonage Service Plans

Vonage VoIP Members
Members List Members
New LelandO930
New Today 0
Yesterday 12
Total 92096

Who Is On Site
Visitors 121
Members 1
Total 122

Vonage VoIP Forum Members:
Login Here
Not a Member? You can Register Here
As a registered member you will have access to the VoIP Speed Test, Vonage Service Announcements and post comments in the
Vonage VoIP Forums

Vonage Stock Price
Value: 6.52
Change:   N/A
Up to 15 Minute Delay

Site Search

Social Bookmarks
 Printer Friendly Printer Friendly

†AK and HI residents pay $29.95 shipping. ††Limited time offer. Valid for residents of the United States (&DC), 18 years or older, who open new accounts. Offer good while supplies last and only on new account activations. One kit per account/household. Offer cannot be combined with any other discounts, promotions or plans and is not applicable to past purchases. Good while supplies last. Allow up to 2 weeks for shipping. Other restrictions may apply.

1Unlimited calling and other services for all residential plans are based on normal residential, personal, non-commercial use. A combination of factors is used to determine abnormal use, including but not limited to: the number of unique numbers called, calls forwarded, minutes used and other factors. Subject to our Reasonable Use Policy and Terms of Service.

2Shipping and activation fees waived with 1-year agreement. An Early Termination Fee (with periodic pro-rated reductions) applies if service is terminated before the end of the first 12 months. Additional restrictions may apply. See Terms of Service for details.

HIGH SPEED INTERNET REQUIRED. †VALID FOR NEW LINES ONLY. RATES EXCLUDE INTERNET SERVICE, SURCHARGES, FEES AND TAXES. DEVICE MAY BE REFURBISHED. If you subscribe to plans with monthly minutes allotments, all call minutes placed from both from your home and registered ExtensionsTM phones will count toward your monthly minutes allotment. ExtensionsTM calls made from mobiles use airtime and may incur surcharges, depending on your mobile plan. Alarms, TTY and other systems may not be compatible. Vonage 911 service operates differently than traditional 911. See for details.

** Certain call types excluded. is not an official Vonage support website & is independently operated.
All logos and trademarks are property of their respective owners. All comments are property of their posters.
All other content is © Copyright 2002 - 2013 by 4Sight Media LLC.

Thinking of signing up for Vonage but have questions?
Business and Residential customers can call Toll Free 24 hours a day at: 1-888-692-8074
No Vonage Promotion Code or Coupon Codes are required at to receive any special,
best Vonage cheap deals, free sign up offers or discounts.

[ | | | | | ]

Vonage Forum Site Maps

Vonage | VoIP Forum | How VoIP Works | Wiring and Installation Page Two | International Rate Plans 2 | Internet Phone
Promotion | Vonage Review | VoIP | Broadband Phone | Free Month | Rebate | Vonnage | Vontage | VoIP | Phone Service
Phone | llamadas ilimitadas a Mexico | Latest News | VoIP Acronyms | Deal | Philippines Globe Phone | Site Maps

The Vonage Forum provides the Vonage sign up Best Offer Promotion Deal.
If you are considering signing up for Vonage and have found our Vonage News, Customer Reviews, Forums
& all other parts of this site useful, please use our Vonage Sign up page.

Vonage VoIP Phone Service is redefining communications by offering consumers
& small business VoIP Internet phones, an affordable alternative to traditional phone service.
The Vonage VoIP Forum Generated This Page In: 0.76 Seconds and 252 Pages In The Last 60 Seconds
The Vonage VoIP Forum