Technical > Photos of Broadband gear > Analog Voice Gateways

reply to BiggA

Re: Analog Voice Gateways

On a 100mbit line, it's unlikely to happen. I don't seem to have issues with my AT&T Microcell when I'm hitting the 'net hard, probably because I have the Microcell god-esque QoS priority in the router.

I do have general upload jamming issues though, so I've cut my torrents, backup, and Google Music down to 1mbps each, but if two or three of them kick on at the same time, or with Dropbox, then everything kind of grinds to a halt on the web browsing side of things.

It's not a question of bandwidth to the internet for many of these campuses, it has to do with QoS and congestion on the internal network. Additionally, the number of lines many of these enterprises have would take a heavy toll in bandwidth (they number in the hundreds, if not thousands). Remember that the average VoIP call takes about 130kbps of bandwidth (counting overhead), or about 80 lines with 10mbps of bandwidth.

I'll give my two cents having designed a network for a higher education campus.

Due to security issues, and the existence of an original PBX, only some lines were replaced with VoIP, notably offices and labs. Classrooms and Emergency phones remained on the PBX due to technology limitations and cost. Each of the VoIP phones needed a new line to be run for every phone since the existing wiring was based off of Cat 3. The network was designed so that voice traffic was independent of the data network to help with latency, security, and network congestion issues. Likewise, the IP cameras on campus are also on an entirely separate network for security reasons. This particular organization uses PoE for the switches at quite an expense, and runs an Avanya PBX system for VoIP, and a Siemens PBX for POTS.

The POTS infrastructure was not transitioned using FXS devices for the simple reason that the existing PBX was in place, and for emergency situations should the core routers fail, the campus would still be able to reach out through conventional means.

The problem with VoIP is that it requires you to have a stable, consistent, and good quality internet connection with little loss. Should your internet connection fail at any time, then you have serious issues about not being able to contact the outside world. "Use your cell phones" is not an acceptable answer to these enterprises.

Why are the bitrates cranked up so high? Cell phones are something like 10kbps.

"Use your cell phones" should be an OK answer, as they will always work. Of course, you could always have a backup internet connection in case one fails...

Standard VoIP bitrates (like G.711) are at least 40kbps, and many are 50 or 64 plus packet overhead. These are land lines that have to be clear to the other end. There's a reason Verizon ran those "can you hear me now?" ads, since 10kbps is terrible quality considering AM radio is 24kbps.

It will never be acceptable to Fortune 1000 companies, especially when people/clients go to call them. Additionally, if you add that much cell traffic, the towers can be overloaded, not to mention the cost of minutes. It just has to work, because that's what you are paid to do. Yes, you always have a backup but even backups fail.

Regular phone systems can bite the dust too, it's not like any of this stuff is super reliable. At least VOIP you could have multiple bandwidth providers as redundancy, as opposed to one phone company where if something blows up.

It's hard to find hard data, but AFAIK, the highest bitrate WCDMA can handle is 23kbps, and WCDMA on the iPhone is higher than landline quality. Admittedly, there's probably a lot of processing going on in the iPhone, but it is able to pull it off.

Not sure if I've ever used a VOIP system, but a good cell phone connection (like AT&T 3G on the iPhone 4S) definitely sounds better than a copper landline. Again, might be processing and massaging, since Apple spends a LOT of time and money on every detail of the thing.

POTS is still more reliable than cell phone service that's for sure. The problem with redundancy I already stated before. I've also previously stated the reason companies keep POTS, mostly due to security and cost.

Higher than land line quality perhaps, but not better than VoIP. Additionally quality is not important in classrooms and for emergencies.

That's subjective and depends on the quality of the line, the distance, the age of the line, the phone handset, and variety of other factors.

OK, maybe VOIP can beat a cell phone, I know Skype has some of the best quality that you'll get on any sort of "phone". Land lines aren't that great, however, as they are analog and have basically no processing power at the end of the line. The best calls that I have are AT&T to AT&T on the cell phone side...

reply to sk1939
Also, why would you have phones in the classrooms? There is no reason to have them, since people are moving in and out of them all the time. My university has the same thing, and it's just a waste of money. As are dorm phone lines, since no one uses them. They should just rip the whole system out.

The phones are there for emergencies, and for the instructor to call for services such as Plant Ops, Security, A/V, etc.

Dorm phones are a legacy from the time before cell phones. Why would you rip out a perfectly functional system that's in place?

I've literally seen professors need to make phone calls, they don't even notice they are there. They just pick up their cell phones anyways. If they put that money towards getting better in-building cell coverage, we would all benefit.

Well, maybe not rip out, but just unplug and let it go dead. There's no reason to keep paying every month to support a system that no one uses.

I'm guessing you're still in college? I myself only just recently graduated two years ago. However plenty of times in real world situations campuses, companies, government etc... require things to be secured, segmented, installed and maintained even if you don't view them as needed. From the world experience I've had so far what sk1939 has said is completely accurate.

Also an example public schools are required to have some type of hardwire communication in the classroom for the teachers to call to the office. I've seen the hardwired phones used many many times in the two universities I've attended to contact plant staff, call for an emergency or other on campus calls. Why have the teacher be required to save 20 phone numbers into their cell phone when they can just use the phone system in the school and call a local extension.
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Edrick Smith
Independent Film & Broadcast Producer
»edricksmith.com

Edrick is right. I work in a public school and we have a copper plant for phone and our network plants.

Our phone system is a traditional PBX with a VoIP card to call other districts in our consortium. In each classroom we are required to maintain a phone jack, two network drops, and a CATV jack. If we don't maintain them, we can not get money from a state grant designed to maintain them.

The problem we have with it is that AT&T put the jacks in illogical locations such as the back of the room when the teacher's desk is at the front of the room.

reply to Edrick
I'm talking higher ed. K-12 makes sense, as the teachers need to be able to communicate with each other, support staff, and the office.

In higher ed, no one would know the numbers anyways unless they are printed somewhere (just as easy to dial on cell), or they Google them and dial them, which would be on their own smartphone anyways.

No one uses them. No one wants them. If there's not good cell service, then that's a legitimate issue that needs to be dealt with, either through repeaters or partnering with AT&T and Verizon to come in and install sites to cover deep inside buildings.

reply to BiggA
It makes sense to run the cable for everything when your running the cable. It's pain all the way around when you have to go back in and run new cable later. It's cheaper to run all of the cable at once than to run it later.

We're finding that out now as we had network drops out of spec when AT&T wired our building 12 years ago. I had to have fiber run and re-deploy a switch to take care of these issues. Just finished lighting it up yesterday.

Truthfully, I would much rather have a phone in the room. It's a safety issue more than anything. And with VoIP some of the endpoints can be moved from room to room and the extension would follow. You can tie the extension to the MAC address to the handset.

kc8jwt, That's absolutely true. Running more cable is always better. That doesn't mean that you need to actually activate it all right off the bat.

No one wants POTS lines that no one uses. Safety? In higher ed, no one even realized the phones are there, or knows if they work or not. Which am I going to use in an emergency? Some wall phone that might not work and no one has used in years, or an AT&T or Verizon smartphone that is a known quantity? I'm picking up my iPhone, thank you very much. I know the call will go through, unlike some crumbly POTS system. Plus, if there are more than a couple of people in a room, there's the built in redundancy of having two carriers, in case one just happened to be suffering an outage that day. That, and if the electricity goes out, who knows what's working and what's not, it's very random as to what's on generators or batteries, but you know AT&T and Verizon have generators that are going to keep things juiced up.