Networking & Communications

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Free VoIP Phone Calls - VoIP Technology is explained in detail

VoIP is break through invention which lets you make free or very cheap local, long distance and international calls. You may have few questions in your mind such as how VoIP works, what are the benefits of VoIP.

VoIP relationship with Computers and Networks.

Put VoIP aside for now and lets start learning about computer networking, you may have heard about computers, networks, switches and wireless networks. Computers communicate with each other via a set of copper wires, fiber optic cables and wireless spectrum waves. Computer communication takes place in the form of data. For example if you are sending an email to someone that email is converted into data packets which are transmitted over the network of computers, switches and routers and when transmitted packets arrives at destination these are again converted back into email. This whole process takes less than few milliseconds to complete. That is how a computer network communication takes place.

VoIP is very similar to computer data communication in nature therefore it is important that you understand how computer data network works.

How VoIP works and how a VoIP call is transmitted over data networks?

Now since we have discovered how computer data network functions therefore it will be easier for us to grasp how VoIP works. VoIP stands for (Voice over Internet Protocol), VoIP calls feel and sounds no different than a standard PSTN call. The only difference is that the VoIP calls are transmitted over computer data networks rather than PSTN exchanges.

When we make a VoIP call, a communication channel is established between caller and called party over IP (Internet Protocol) which runs on top of computer data networks. A telephony conversation that takes place over VoIP are converted into binary data packets streams in real time and transmitted over data network, when these data packets arrive at the destination these are again converted into standard telephony conversation. This whole process of voice conversion into data, transmission and data conversion into back voice conversation takes place within less than few milliseconds. That is how a VoIP is call is works over data networks. I hope that now you understand basics of how a VoIP call takes place.

What are speech codec's and what role codec plays in VoIP?

Speech codec play a vital role in VoIP and codec determines the quality and cost of the call. Let me explain you what exactly VoIP codec’s are and how they work. You may have heard about data compression, or probably you have heard about air compressor which compresses a volume of air in enclosed container, VoIP codec’s are no different than a air compressor. Speech codec’s compresses voice into data packets and decompresses it upon arrival at destination. Some VoIP codec’s can compress huge amount of voice while maintaining QoS which means use this type of codec will cost less because it will consume just a fraction of data network. Some codec’s are just not capable of encoding huge amount of voice they simply consume huge amount of data networks bandwidth hence the cost goes up.

Following is a list of VoIP codec’s along with how much data network bandwidth they consume.

* AMR Codec
* BroadVoice Codec 16Kbps narrowband, and 32Kbps wideband
* GIPS Family - 13.3 Kbps and up
* GSM - 13 Kbps (full rate), 20ms frame size
* iLBC - 15Kbps,20ms frame size: 13.3 Kbps, 30ms frame size
* ITU G.711 - 64 Kbps, sample-based Also known as alaw/ulaw
* ITU G.722 - 48/56/64 Kbps ADPCM 7Khz audio bandwidth
* ITU G.722.1 - 24/32 Kbps 7Khz audio bandwidth (based on Polycom's SIREN codec)
* ITU G.722.1C - 32 Kbps, a Polycom extension, 14Khz audio bandwidth
* ITU G.722.2 - 6.6Kbps to 23.85Kbps. Also known as AMR-WB. CELP 7Khz audio bandwidth
* ITU G.723.1 - 5.3/6.3 Kbps, 30ms frame size
* ITU G.726 - 16/24/32/40 Kbps
* ITU G.728 - 16 Kbps
* ITU G.729 - 8 Kbps, 10ms frame size
* Speex - 2.15 to 44.2 Kbps
* LPC10 - 2.5 Kbps
* DoD CELP - 4.8 Kbps

What are VoIP Devices, VoIP Phones and VoIP PBX?

VoIP device are mini computers, they contain CPU, Memory (RAM), ROM, Software, Operating Systems, Speech Codec’s and they are customized to work as VoIP device. These devices are responsible for converting voice conversation into data streams, data compression, decompression, transmission, ring tones, bells and etc,. In order to use VoIP devices you will need to connect your standard PSTN, or a cordless phone to make and receive calls.

VoIP phones are no different than a VoIP device, they contain VoIP device plus a built-in phone, as explained above VoIP phone also contains CPU, Memory (RAM), ROM, Software, O/S and codec’s. Some VoIP phones also contain a LCD screen which you can use as a internet browser.

VoIP PBX (Private Branch Exchange) are mini telephone exchanges, VoIP PBX are full computer server type hardware which contains OS, FXS, FXO, T1, PRI, E1 and various other telecommunication interfaces. Many VoIP PBXs also contains all the above mentioned speech codec’s which can be selected as a preferred codec. VoIP PBX can provides hundreds of features and extensions. To find out more about VoIP PBX read the last paragraph of this article.

What role a VoIP VoIP Providers plays?

VoIP providers play a vital role with provisioning your internet phone service. They are responsible for terminating your voice calls to different VoIP and PSTN networks. VoIP providers have agreements and arrangements with other VoIP service providers all over the world in different countries for exchanging, terminating and origination of VoIP and PSTN calls. Some VoIP providers will let you make free unlimited calls for a fixed amount of money.

To find out which VoIP service provider is best suited to your needs please visit following website. VoIPBazar.com

What features are available with VoIP Technologies?

ADSI On-Screen Menu System
Alarm Receiver
Append Message
Authentication
Automated Attendant
Blacklists
Blind Transfer
Call Detail Records
Call Forward on Busy
Call Forward on No Answer
Call Forward Variable
Call Monitoring
Call Parking
Call Queuing
Call Recording
Call Retrieval
Call Routing (DID & ANI)
Call Snooping
Call Transfer
Call Waiting
Caller ID
Caller ID Blocking
Caller ID on Call Waiting
Calling Cards
Conference Bridging
Database Store / Retrieve
Database Integration
Dial by Name
Direct Inward System Access
Distinctive Ring
Distributed Universal Number Discovery
Do Not Disturb
E911
ENUM
Fax Transmit and Receive (3rd Party OSS Package)
Flexible Extension Logic
Interactive Directory Listing
Interactive Voice Response (IVR)
Local and Remote Call Agents
Macros
Music On Hold
Music On Transfer:
- Flexible Mp3-based System
- Random or Linear Play
- Volume Control
Predictive Dialer
Privacy
Open Settlement Protocol (OSP)
Overhead Paging
Protocol Conversion
Remote Call Pickup
Remote Office Support
Roaming Extensions
Route by Caller ID
SMS Messaging
Spell / Say
Streaming Media Access
Supervised Transfer
Talk Detection
Text-to-Speech (via Festival)
Three-way Calling
Time and Date
Transcoding
Trunking
VoIP Gateways
Voicemail:
- Visual Indicator for Message Waiting
- Stutter Dialtone for Message Waiting
- Voicemail to email
- Voicemail Groups
- Web Voicemail Interface
Zapateller

VoIPBazar proudly promotes VoIP Technology and provides information how to make free or cheap calls to over 10,000 cities across the globe.

About the Author

Imran Khan is author related to following websites and he writes passionately on various telecommunication topcis.

http://www.voipbazar.com

http://www.voipbazar.com/shop/index.php

http://www.voipbazar.com/shop/index.php/mobile

http://www.voipbazar.com/forum

Ethernet Cable Video Extender Problems?

I've bought a few Black Box video/usb extenders, and also an off brand which I cannot recall that brand ATM, but it's worse. The runs are from around 30 feet to 80 feet, either run in conduit or in open cable tray with nothing else in the tray except a few other video/usb extenders. According to Black Box, they should work fine. DIP switches have been set to either the close range or the long range with the same results.

But, the LCD monitors blink off, and then back on quite randomly and quite frequently. I hooked up a Fluke tester and the run qualifies for VOIP and has negligible induced noise. (I don't know if the tester ever says there is no noise)

I am at wits end. Does anyone know a "trick", like possibly grounding one of the conductors, or maybe have solved this problem with a different product? Or maybe know what the problem is? Or are all these extenders pieces of crap?

Those dang things cost a lot of money.

The extender adapters should easily convert to handle USB. Video is not as easy.The slightest thing can upset the signalling. And a reduction in voltage over the line will cause a monitor to drop out.The cables need to be unshielded twisted pair or shielded with ONE end shield grounded. and forget the fancy testers, I have seen them pass cables to Gb performance, but they won't run a simple phone due to load if the connections are not correctly made. Monitors are quite a load and an insecure crimp will seriously affect performance on a cable which will run correctly for networking. Bad quality RJ45 connectors, using the incorrect crimping or IDC tool (there are 3 types of IDC connectors) or just a worn crimping tool can cause these problems. And if ANY other cable running parallel has a problem it can affect all cables in the vicinity. Also if a trunk, rack or tube runs parallel and close enough to a mains power cable it can induce high voltages. I have powered a 110v bulb from a CAT6 cable this way to demonstrate the problem. That circuit running 2 tubes side by side (240v in one CAT6 in the other) had actually destroyed a £7,000.00 UK machine.

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