Sunday, 18 September 2011

VoIP international calls

VoIP international calls

To be masterly to start making VoIP intercontinental calls, it is certain for you to initially get registered with a VoIP serving provider. You have to identify that there are multitudes of advantage providers out there, so you difficulty to pick the perfect one. This pick is dependent upon the amount of in money that you can waste. The low-down is that the meet amongst VoIP checking providers is constantly increasing and they take off no stones unturned to preserve continue their being in the land of the living sensitive in the minds of the consumers. Evidently, all of them are out to seize the biggest deal of the vend, which is why they are in any case gift something one and only and innovative so people would be enticed to try them out. All of the VoIP appointment providers advance separate work plans with which they extend a as much as possible radius of facilities so that all of the requirements of their subscribers are fulfilled. How assorted of us memorialize the phone numbers of undisturbed five of our friends? When you for a apostrophize b supplicate on your smartphone, you don't exemplar in the phone mass - you click on the individual's specify identify as a substitute for. We as humans experience a elementary lack to thwart in movement with each other. The fulfillment of this poverty is basically dependent on the equanimity of a complete speciality fad, which would send excited status calls at an outrageously prudent anyway. VoIP providers. This essential merciful for leads to the introduction of VoIP or Make known finished Internet Customs. With this enthusiastically innovative technology, you can clearly overstate calls using the internet. The choicest take a hand in here VoIP is that it does not desire any additional materiel and even-handed needs you to be dressed a computer with a broadband connecting together with a headset and microphone! Making calls to the core VoIP has a copy of benefits. Its moderate figure is even so the most influentially sought betterment these days.
Making ecumenical calls using a old-fashioned phone mark is uncommonly precious and valid cannot be afforded on a classic principle. Requite if a extensive remoteness phone is made, the discourse needs to be shortened. Voip review. This is why VoIP allows users to originate intercontinental calls without having to fret far the spinach that they would cause to pay. To be proper, there are undisturbed VoIP global calls parcel plans, which own you to exclusively judge calls to the most non-professional countries. So before selecting a calling aim, attack solid that you go from one end to the other its details and then umpire fix which one works crush for you. With the progress in technology, we now suffer with haler options in terms of communication. Making eat one's heart out interval calls was in days gone by considered a stupendous delight, because of the on a trip charges that one had to pay for them. Now, thanks to the extraordinary advancements in technology, the absolute superb is more closely heal and people now discover it much easier (and cheaper) to figure out wish mileage or worldwide phone calls.

Making using virtual DID numbers in Istanbul

Making cheap calls to Turkey using virtual DID numbers in Istanbul

Turkey's local name is Turkiye and it is known officially as the Republic of Turkey. It is a Eurasian country located in Western Asia. Turkey is bordered by eight countries: Bulgaria to the northwest; Greece to the west; Georgia to the northeast; Armenia, Azerbaijan and Iran to the east; and Iraq and Syria to the southeast. The capital city of Turkey is Ankara. Turkey is divided in 81 different provinces and provinces are further divided into 7 regions.

 How to dial Turkish phone numbers: 

  • "0" is the long distance dialing code in Turkey and must be added long distance.

  • Area codes are three digits long and every city has its own area code.

  • Turkish phone numbers are 7 digits

  • Dialing mobile numbers is a long distance call and needs to be dialed as 0 + mobile code + number 
How to call Turkey from other countries:
Phone numbers are frequently shown with the plus + sign in front of the number + 90 212 122 1515. 90 - country code for Turkey. Area code - 3 digit area codes. Cellphones also have 3 digit codes starting with "5". Phone number - 7 digits
 Costs of calling Turkey from other countries: dialing Turkish numbers from outside Turkiye can be very expensive. Let's look at various options available for calling landlines and mobiles in Turkey. 
1. VoIP providers offering discount rates for international calls.
 Voice over IP services like Broadvoice, Skype, Lingo and Vonage offer affordable rates to dial international. Using these services, you will pay less per minute than you would pay by dialing Turkey directly. It will cost you about $0.17 to dial landlines in Turkey and up to $0.58 to call mobiles.
2. Calling cards (US and Canada)
Union Telecard, one of the largest calling card brands in North America, provides convenient service with many access numbers across the country. Per-minute rates to dial Turkey are from $0.06 for landlines and $0.28 for mobiles.
3. Virtual number providers – save up to 95% by using DID numbers in Turkey instead! 
There are several alternative VoIP providers offering much cheaper service to Turkey without a compromise on quality. Savings are achieved by using virtual telephone numbers from Turkey (Ankara, Istanbul). This technology offers free and unlimited falls from $10 per month – no calling card or VoIP device is required. 
For example, Didlogic.com, WorldNX, CTS and CMN provide Istanbul, Izmir, Ankara and National virtual numbers in Turkey that can be helpful in cutting your costs dramatically. You can now have a DID number in Turkey that can be forwarded to any phone in the world or sent to your other SIP provider, or Skype account.
Outgoing calls to Turkey cost only $0.02 per minute to landlines and $0.05 to mobiles.
You can also buy a Turkey phone number and forward it to your cellphone anywhere in the world. Your call history and caller IDs can be viewed online by logging in to your online account. You can easily change your forwarding destination by logging in to your account.
You can create local presence in Instanbul, Turkey without having to establish an office and invest in company formation. Virtual numbers are a very convenient way to provide your callers a local number to dial that will be diverted to any phone worldwide, or an IP address. Ankara, Istanbul, Izmir or National Turkey DID numbers can also be integrated with your virtual PBX or SIP server like Asterisk or FreePBX.
This same option can be used to make calls to other destinations in Europe, North America and Central Asia: Canada - $0.0026/min USA - $0.0056/min UK - $0.007/min Kazakhstan - $0.0066/min
Pricing heavily depends on the cellular network you are dialing. Even though DIDlogic.com service can cost more for various numbers in the same country, many networks are extremely affordable to call. This is a very simple and convenient option to save money on your calls to Turkish mobile phones and landlines. You can provide over 95% on your international calls.

Wednesday, 24 August 2011

VoIP Phone- Advanced Flexible Telephonic Technique Reduces Call Cost

VoIP stands for voice over internet protocol; VoIP phone is an advanced telephonic technique that is used to make calls through the internet and to transfer the voice to any internet user and any land-line phone as well. 



At present VoIP phones are used a lot as these are the best solutions among all the telephonic techniques available in the world. These phones are very advantageous and do not require a huge investment. VoIP phones always require a high-speed internet connection like broadband and VoIP hardware only. 

VoIP is increasing in its popularity because it allows the user to make long distance calls for free in some cases or at very cheap rates. VoIP provides quality services at low cost and also have some incredible features. It is also used as a business solution worldwide so gaining popularity in business as well. 

If any person do not want to purchase a VoIP phone, but still wants to make use of VoIP services, it can use it through its conventional phone. This can be done using techniques available like PBX gateway, etc. that enables any conventional phone to make VoIP based calls. Using this technique the installation cost is also reduced for the VoIP phone and it is a powerful tool for different organization available worldwide. 

There are a lot of advantages of VoIP phones that made it so popular and useful for everyone throughout the world.  Some of the advantages are listed below:

1.    The VoIP phones are available in the market at very low cost. The cost included in the installation is not so high and can be used in the same cost as any conventional phone.

2.    The call cost can be reduced to a large extent using VoIP phones. This is the main advantage of VoIP phone, enables the user to make long distance calls at affordable price and sometimes free calling is provided as well.

3.    There is no requirement of a huge investment to use VoIP as only internet connection and VoIP hardware is needed.

4.    The govt. does not charge too much tax for using VoIP phone as internet is used to make calls.

5.    VoIP provides some extra features as well like, call forwarding, caller ID, call waiting, 3 ways calling, etc.

6.    One more advantage of VoIP phone is that it provides flexibility, i.e. it can be used anywhere in the world and one can take this anywhere with him/her.

As we saw various features and advantages of VoIP so in short it can be concluded that VoIP phones are very useful and should be used to reduce the calling cost.

Voip H.323 Definition

H.323 standard is defined by the International Telecommunication Union (ITU), which states that the protocols to provide audio-visual communication sessions on packet switched network.

The H.323 standard addresses call signaling and control, multimedia transport and control, and bandwidth control for point-to-point and multi-point conferences.
It is widely implemented by voice and videoconferencing equipment manufacturers, is used within various Internet real-time applications such as VoIP, Video conferencing over IP.
H.323 is now considered to be the standard for interoperability in audio, video and data transmissions as well as Internet phone and voice-over-IP because it addresses call control and management for both point-to-point and multipoint conferences as well as gateway administration of media traffic, bandwidth and user participation.
What are H.323 Components?
Terminals
Terminals are the client endpoints on the LAN that provide real-time bidirectional multimedia communications. An H.323 terminal can either be a personal computer (PC) or a stand-alone device, running an H.323 stack and the multimedia applications.
It supports audio, video and data communications. H.323 specifies the modes of operation required for different audio, video and/or data terminals to work together.
H.323 terminal plays a key role in IP-telephony services, and is the dominant standard of the next generation of Internet phones, audio conferencing terminals, and video conferencing technologies.
Gateways
A gateway connects two or more networks. An H.323 gateway provides connectivity between an H.323 network and a non-H.323 network.
For example, a gateway can connect and provide communication between an H.323 terminal and TDM networks (Time Division Multiplexing networks include all switched telephony networks, e.g., PBX, public switched telephone network [PSTN]).
The connectivity of dissimilar networks is achieved by translating protocols for call setup and release, converting media formats between different networks, and transferring information between the networks connected by the gateway.
For example, in the case of video conferencing a gateway may be required to call H.323 end point or VC in remote site and also to call a VC in remote end point on ISDN.  Basically gateways convert TDM traffic to IP packets.
Gatekeepers
The gatekeeper is the most important H.323 components. The gatekeeper's primary job is to act as the central point for all calls within its zone and provide call control services for registered H.323 endpoints.
Basic function of the gatekeeper is address translation, Calls originating within an H.323 network may use an alias to address the destination terminal. Calls originating outside the H.323 network and received by a gateway may use an E.164 telephone number to address the destination terminal.
The gatekeeper must be able to translate the alias or the E.164 telephone number into the network address for the destination terminal. The destination endpoint can be reached using the network address on the H.323 network. The translation is done using a translation table that is updated with Registration messages.
For example in Voice over IP which is driving voice traffic over IP network, we dial the extension number of the remote IP phone. IP network only handles IP not decimal numbers, because we cannot remember IP address of remote equipment we are dialing by number.
This conversion of decimal numbers to IP address and IP address to decimal number is done by gatekeeper. Besides these function gatekeeper also does Admission Control, Bandwidth Control, and Zone Management.

VoIP Quality of Service VOIP SERVICE

This section aims to explain some of the issues that should be considered when planning a VoIP installation or prior to the installation. It should be noted that this section contains a general view of VoIP implementation. IP is today widel used for Voice Video Data purpose

VoIP Quality of Service: (QoS) is one of the most important factors for VoIP. The term refers to the perceived quality of speech and the methods used to provide good quality speech transmission since voice is real time application. There are several factors that affect speech quality, and several mechanisms that can be used to ensure QoS.
This section describes the problems that can occur and some possible solutions. Each network equipment manufacturer will have slightly different methods of implementing QoS and these are not discussed in this document. This is just to give an overview and to explain how we can classify voice traffic so that the network equipment can impose QoS.
What is Latency: Latency is delay, if at any point the usage on the network exceeds the available bandwidth, the users will experience delay, also know as latency. In more traditional uses of an IP data network, the applications can deal with this latency. If a person is waiting for a web page to download, they will accept a certain amount of wait time. This is not applicable for voice traffic. Voice is a real time application, which is sensitive to latency.
If the end-to-end voice latency becomes too long (>250 ms, for example), the call quality would usually be considered to be poor. Another important thing to remember is that packets can get lost. IP is a best effort networking protocol. This means the network will try its best to get your information there, but there is no guarantee.
Delay is the time required for a signal to traverse the network. In a telephony context, end-to-end delay is the time required for a signal generated at the talker's mouth to reach the listener's ear. Therefore end-to-end delay is the sum of all the delays at the different network devices and across the network links through which voice traffic passes. Many factors contribute to end-to-end delay.The buffering, queuing, and switching or routing delay of IP routers primarily determines IP network delay. Specifically, IP network delay is comprised of the following.
Packet Capture Delay: Packet capture delay is the time required to receive the entire packet before processing and forwarding it through the router. This delay is determined by the packet length and transmission speed. Using short packets over high-speed networks can easily shorten the delay but potentially decrease network efficiency.
Switching/Routing Delay:
Switching/routing delay is the time the router takes to switch the packet. This time is needed to analyze the packet header, check the routing table, and route the packet to the output port. This delay depends on the architecture of the switches/routers and the size of the routing table.
Queuing Time:
Due to the statistical multiplexing nature of IP networks and to the asynchronous nature of packet arrivals, some queuing, thus delay, is required at the input and output ports of a packet switch. This delay is a function of the traffic load on a packet switch, the length of the packets and the statistical distribution over the ports. Designing very large router and link capacities can reduce but not completely eliminate this delay.
Jitter:
Delay variation is the difference in delay exhibited by different packets that are part of the same traffic flow high frequency delay variation is known as jitter. Jitter is caused primarily by differences in queue wait times for consecutive packets in a flow, and is the most significant issue for QoS. Certain traffic types-especially real-time traffic such as voice, are very intolerant of jitter. Differences in packet arrival times cause choppiness in the voice.
All transport systems exhibit some jitter. As long as jitter falls within defined tolerances, it does not impact service quality. Excessive jitter can be overcome by buffering, but this increases delay, which can cause other problems. With intelligent discard mechanisms, IP telephony/VoIP systems will try to synchronize a communication flow by selective packet discard, in an effort to avoid the "walkie-talkie" phenomenon caused when two sides of a conversation have significant latency.
Packet Loss:
During a voice transmission, loss of multiple bits or packets of stream may cause an audible pop that will become annoying to the user. In a data transmission, loss of a single bit or multiple packets of information is almost never noticed by users. If packet drops become epidemic, then the quality of all transmissions degrades. Packet loss rate must be less than 5% for minimum quality and less than 1% for toll quality.
Voice Quality Improvements:
There are various techniques that can be used to improve the voice quality, including:
a) Increase the available bandwidth
This can sometimes be the most basic solution and the easiest of the solutions. If someone is running a IP Phone using G.711 with a 30ms fill time over Ethernet, for only one call, they need 83.7Kbps worth of bandwidth. If that same user only has a 64K line, they are not going to be able to have a decent IP voice call. The user can simply increase the available bandwidth to slightly exceed the 83.7Kbps requirements and their voice quality will dramatically increase. This solution might not be viable if no more bandwidth is available.
b) Use a different CODEC
The CODEC contains possible compression algorithms to be used on the voice. Lets take the example above again. The user only wants one voice line over a 64Kbps data connection. They also want to maintain their current fill time of 30ms. So, lets change to a G.729. Now for one line, only 27.7Kbps is required for a call. This fits well within the 64Kbps of available bandwidth.
c) Increase the number of frames per packet
To continue with the example above, the user has moved to a G.729 CODEC. But now, the user wishes to add two more IP Phones. Their current 64Kbps line can handle one call, because it is only 27.7Kbps. Two more IP Phones would increase the total to 83.1Kbps so obviously there is not sufficient bandwidth.
The user can now increase the fill time to 50ms. This would then reduce the bandwidth per call to 19.8Kbps (3x 19.8 = 59.4Kbps). The savings in bandwidth comes from the fact that with a longer fill time, fewer packets are needed to send the voice. With fewer packets there is less header information that needs to be attached and transmitted.
d) Change Layer 2 Protocols
Ethernet is most commonly used for IP packets. Unfortunately Ethernet has a fairly large overhead of 34 bytes. So every IP voice packet going over Ethernet is going to have a 34 byte Ethernet header attached to it. As the number of packets add up, this amount of header data can become significant. Frame Relay has a 7-byte header and Point-to-Point Protocol (PPP) has a 6-byte header. With this decrease in header length at layer 2, some significant savings in bandwidth use can be achieved.
The down side to this is that most networks may not have these services available, where Ethernet is very widely used. This is usually outside the control of the installer and therefore we need to do more research on other layer 2 protocols before trying to implement them in their voice network.
e) Implement Quality of Service (QOS)
Now, assume a derivative of the above example. The user needs only one voice line over their 64Kbps connection. They are using G.729 with a 30ms fill time. This will require 27.7Kbps of their available bandwidth. Let us now also assume that this line is used at certain times of the day for data connectivity. This data connectivity is very light, only 20 Kbps or so during most of the day, but does spike to 50 Kbps during certain points of the day. This data is not time sensitive like the voice data, so if necessary it could be forced to wait.
Therefore the user can implement a Quality of Service mechanism on the IP network. At its most basic form, this denotes certain IP packets as being more important than others. So they would tell this 64Kbps line that IP packets with voice deserve a higher priority than those without voice. This would allow the network devices to give priority to the other data, so the quality of the call will not be compromised.
Classification of Traffic for QoS:
Classification uses information from a packet (or frame) to define the type of data and therefore how the data should be handled for QoS on the network. Using packet classification, you can partition network traffic into multiple priority levels or Types of Service (ToS).
VLAN (802.1Q):
Virtual LANs work at Layer 2 of the OSI model and can be equated to a "broadcast domain". More specifically, VLANs can be seen as a group of end stations, perhaps on multiple physical LAN segments that are not constrained by their physical location and therefore, communicate as if they were on a common LAN. Packets can be marked as important by using layer 2 classes of service (CoS) settings in the User Priority bits of the 802.1Pq header.
IP Precedence - Layer 3 QoS:
Allows you to specify the class of service for a packet. You use the 3 precedence bits in the Ipv4 header's type of service (ToS) field for this purpose. Using the ToS bits, you can define up to 6 classes of service. Other devices configured throughout the network can then use these bits to determine how to treat the packet in regard to the type of service to grant it. These other QoS features can assign appropriate traffic-handling policies including congestion management and bandwidth allocation. By setting IP Precedence levels on incoming traffic and using them in combination with QoS queuing features, you can create differentiated service.
Differentiated service (Diffserv) - Layer 3 QoS:
Provides services differentiated on performance utilising weighted priority queuing. Diff-Serv requires that edge routers classify traffic flows into a member from a set of categories based upon the TCP/IP header fields in what is called a micro flow. Because the Diffserv is present in every packet header, each node can provide differentiated services on a per-hop basis.
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