How To Live Free - Part 5 0f 5: Finally VOIP (Asterisk)
The reason this last chapter took so long is because like most of you I work for a living so I needed time to implement before I write a blog. The Professor doesn’t like to provide information unless he has did it himself. (I sound like Kobe Bryant with the 3rd person).
I have been involved in VOIP on and off for 10 years. So I have been eager to see it develop into an everyday phrase. There is not a phone call being made during the day that does not involve VOIP to some degree. Even if you still have that Verizon line at home and haven’t given in to Vonage, Comcast, or Time Warner, you have to know that even your TDM Verizon connection traverse a backbone of H.323 and SIP trunks to make it to the DS0 that is connected to your Grandma’s rotary dialed telephone.
Professor’s Conspiracy Theory
Q1: If the government can force you to go digital television, why won’t they force you to go VOIP?
Q2: If I purchased VOIP service from Comcast or Verizon, then why haven’t they converted my traditional lines with the same lines I use to connect my computers? (Cat5)
Q3: I hear about VOIP, I even have Voip service, where are all the bells and whistles?
Like you I have always asked these questions. When you order VOIP service from Vonage, they provide you with an ATA to convert your analog to digital. They also provide 802.11 and regular ethernet VOIP phones for you to connect to their service. They are not a big enough outfit to provide CAT5 cabling to you as well, but for the most part they provide the cheapest offering because they only have to invest in their core and infrastructure. You depend on your Internet Service Provider.
When you purchase VOIP service from Comcast, they have already done the math. They connect your Telephony Demarcation directly to the MTA so that all of your phones will not be changed and all of your existing wiring will be used, rerun or maintained.
This isn’t because they are making your life simpler. Your life would be simpler if you can purchase an 802.11 (wireless) cordless phones and have video conferencing from an IP handset in your bathroom. Softphones for remote travel options. In other words, IP flexibility. However, think of all of the money Comcast will lose if they no longer had to send a tech to your house because your know using 802.11 wireless router from Best Buy, which is plug and play, and not have to send a tech to search your wires and charge you $90 per hour. Dem boys are Union!!
Comcast has the technology to provided these services. They also have the technology to provide ip presence and other IP related features that exist today. But they don’t.
Okay, Asterisk: How to live free!
What exists in the market today are two different models to support subscribers. An IP PBX and a Class 5 server. Both are similar in terms of provisioning application based services, but are different in terms of scalability. You will not configure a PBX to handle 10k CAPs. (Call Attemps Per second).
Asterisk is an IP PBX. Asterisk can provide voicemail, text to voice, voice to text, trunks, extentions, anything a TDM pbx can provide. Asterisk is more or less a core system. You will have to provide a front end. Other than that I would put Asterisk against any of the PBX’s that I have experience on. Such as the Nortel CS2k/ CS2100 and the Cisco Call Manager.
For the purpose of this lesson, I will tell you how I use Asterisk and how it provides a very cheap and flexible alternative for my home living. I have built an Asterisk server for the sake of providing a cheaper service. Asterisk is free, however the time it took to compile and get working was less than 8 hours. There are many white papers that would assist you out on the web.
Cost: Minimal. I used an old computer with a P4 processor. I purchased refurb for $150. I did not purchase a Digium card used to connect to TDM trunks. So I am not using a T1 or DS0 to connect. This is a purely sip connection. So total price of hardware would be $150
Service: I chose to go with a very lightweight service provider. The quality is not perfect, but it isn’t bad either. I am tinkering around that 50ms range which becomes noticeable. But I am pay $14 a month for the service and a DID.
So with $14 a month I am connected to a Sip service provider and I am paying .0012 per call globally. With comcast I pay $19 a month for all US calls. So if I am just comparing Nationally based calls then I make a very minimal profit due to quality concerns.
Applications:
Voicemail is additional with phone service. It is included with Asterisk. Nice part is that with Asterisk you can do what you want with your Wave file. What I have done is configured my Asterisk server to email my wave file to me when I get a call. What I am working on is providing voice to text emailing. There are services out there that I can send my WAV file and they email it back transcribed, but that thats the fun out of it. So bottom line is free.
SMS: Now Comcast supports SMS to Voice services for free. Right now it is a demo, but there is a Perl module that you can use to send SMS to a public SMSC that will forward your messages, but that will take text to voice and I am not a big fan of text to voice. So until that changes I will not be doing this.
Mobility: I can connect to my IP PBX via a soft client. I use many of them and they are all free. One that is readily accessible is Xlite. Comcast has yet to support softclients so this is an added bonus.
Now the way I have my service configured is that everyone in my home is a different extension. So I only have one DID, but for an additional 10 bucks I can get more DID’s. There are other services cheaper, but the total cost of the sip trunk goes up. I don’t need that. I rather have an operator ask you want extension you would like.
Manageablility:
Now you do have web access for Comcast, just like I have web access to my server and any subscriber has access to alter his/her account. I like mine better because it is free. But you can go on the server and look at your voicemail in .WAV files.
Asterisk is a very cool tool that is free and very customizable. I like using pure IP, but you can purchase a card that will have you connect via TDM if you wanted to do so. Only problem I had is RTP proxy. You must have a firewall that does RTP proxy or your voice will never make it in. I use Ubuntu as a firewall so I compiled it very easy. And it is activated in my ipchains rules when every my firewall is restarted.
For a medium sized organization looking to go VOIP, this would be a perfect solution. Even for a large size corporation if you scale it correctly. However, Asterisk is not for the technically weak. So you must be willing to get your hands dirty and your solutions hat on hand. Enjoy.
May 30th, 2008 at 8:42 pm
I worked with SBC 34 years Comm Tech tester..we worked with voip in its infancy Bell was using on their lans..about some 15 years ago.,,The trouble we experinced with this data packet transport was a lot of echo delay…far end..we determined that echo cancellers at far end central offices were causing the problems..also we had some ec’s connected withing the network trunking between c.o.’s that cause problems. We had two types of echos..we called them delay and hallway echo..the hallway eho was trouble at the near end..usaully caused by hybrids networks….like isdn x25, we played around with voip vedio transport using a higher protocol and it seemd to work well.
But thats another story…
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