1. Faulty electrical connection near Internet modem/router. Faulty electrical connections can be caused by bad cabling and loose connections. If it’s a cable modem, the modem must be attached to the first cable split and preferably the connection with the greatest signal level. If it’s a DSL circuit, no other cables should attach to the circuit between the telephone company box and the DSL splitter.

2. DSL circuit frequency interference. If it’s a DSL circuit, interference from other circuits in the telephone company’s cable bundle can cause packet loss, latency and outages. T1 circuits are prone for causing problems. T1 circuits installed in neighbors’ offices can interfere with DSL.

3. Interference from WiFi radio in Internet Modem/Router. Some Internet companies supply modems and routers with built-in WiFi access point capabilities. The built-in access point can be convenient, but it can play havoc with the modem/router itself. WiFi operates in the 2.4 Ghz frequency range. That is the same for many cordless phones and microwaves. Using any 2.4 Ghz device in close proximity to the WiFi enabled modem/router can overload the receive side of a WiFi radio and could cause many problems including device resets. This is true even if the WiFi is not being used as long as the radio is turned on. Make sure the WiFi radio is turned off in software programming for any Internet modem/router. If WiFi is needed, install a stand alone access point.

4. Virus, Worm or Trojan on a PC. Viruses, worms and Trojans can do more than just slow down a PC, they can slow down an entire network. Depending on what they are doing, they can be sending out significant network traffic that can slow down an internal network and give the appearance that the Internet is slow. They can also be sending traffic out to the Internet which would indeed slow down the Internet because they are consuming such a large quantity of bandwidth. It is wise to check PCs for malware anytime a network is slow for no apparent reason.

5. Quality of Service (QoS) Parameters Are Not Set Appropriately for the Available Internet Speed. When Voice over Internet Protocol (VoIP) is being used as well as other realtime data applications, many companies install/program QoS parameters into their Internet routers. One field in the configuration is the amount of available bandwidth. The router must know this in order to know when it is time to employ packet prioritization. It also means that the router will not pass through any more bandwidth then this availability setting even if more is available. If QoS settings are active in router configurations, make sure they are appropriate for the available bandwidth.

6. Congested ISP. ISPs frequently become congested during heavy traffic and sometimes during normal traffic use. Congestion can also happen between routers in their network and are especially prevalent in meet points between two ISPs. Detecting ISP congestion requires monitoring the Internet circuit with an ISP Packet Loss and Delay Test Tool. If the problem is intermittent, then the tool must monitor over an extended period of time such as several days or even a week.

7. ISP Not Delivering Promised Speed. Unless the Internet connection is a fixed circuit such as a T1, the delivered bandwidth from an ISP can vary throughout the day. Typically, the varied rate is due to congestion but it can be other factors as well. Still the rate can frequently be below the expected bandwidth. Speed tests can help determine the delivered bandwidth at a precise moment in time. Be careful, as speed tests results can frequently be misleading and they measure only what is happening at one moment versus an extended period of time.

If you are connected to the Internet but it is not performing as it should, the first step is to start a ISP Packet Loss and Delay Test on the IP address. This test will determine whether the problem is predominantly in or around the home/office of the IP address or somewhere within the ISP.

Not every VoIP implementation is a success story, though. VoIP problems such as dropped calls and garbled speech can be frustrating to users and counterproductive to business. These voice quality problems can be the result of many factors including insufficient Internet speed, poor ISP service, wiring, viruses, improper voice packet prioritization and many more. Solving these issues can seem difficult especially if they are intermittent.

What Not to Do

Do not start changing settings and equipment without a plan. VoIP issues can be caused by dozens of factors including the Internet Service Provider (ISP). Potential trouble areas must be systematically eliminated.

Do not give up on VoIP and its many benefits. Your problem can be fixed.

How to Find the Source of VoIP Problems

VoIP quality problems are caused by a lack of available bandwidth at the time that it is needed. Does this mean purchasing more bandwidth from the ISP will solve the problem? Maybe, but more than likely, no. It means that if there was always enough bandwidth, there would not be any call quality trouble. It also says that the area of congestion will be indicated by packet loss and/or latency.

For packets to travel from one point on the Internet to another, they must pass through a series of routers or hops. Each router examines the destination address of the packet and chooses the next router to send the packet. This process happens about 15 to 25 times on average until the packet reaches its destination on the Internet.

Each router is limited on how much data it can send to the next or throughput. Throughput on an IP connection is determined by physical bandwidth, errors and central processing unit (cpu) capacity. If errors are occurring, then throughput is lowered by retransmission of packets or by the equipment automatically lowering speeds to achieve more reliable communication. When more packets must pass through a point than throughput will allow, the packets are placed into a queue waiting their turn causing latency. If the queue gets full, packets are dropped causing packet loss.

Finding areas of packet loss and latency will narrow down the source of VoIP trouble. Use the HostMyCalls Packet Loss and Delay Test Tool to do that. If your problem is intermittent, have the tool monitor your IP address for several days. You can check the report in progress at any time.

If the report indicates packet loss or latency on a hop going between your ISP and another ISP immediately before, then a congested ‘meet’ point between the two ISPs can be causing trouble. Open a DOS command prompt and type “tracert” followed by the IP address your VoIP calls are going. If they same two routers are in the route, then they could be causing trouble.

If the report indicates packet loss or latency at an intermediate hop within your ISP and the packet loss or latency effects your Internet connection, then that router is likely a source of trouble. In the above two examples, your ISP will have to solve the problem or you will need to change providers.

If the report indicates lost packets on your IP address with minimal or no lost packets on the preceding hop or a large jump in latency, then there is a problem at your site.

Eliminating the Sources of VoIP Problems at Your Site

Many factors can cause packet loss and latency (and therefore poor voice quality) at your site. Cut the factors in half by simply disconnecting everything from the modem/router and run the packet loss and delay test tool again. If the report indicates the same level or trouble, then the problem is the modem/router itself (faulty or overheating), cabling and/or signal to noise ratio. Your ISP may have to help with these.

If the report does not indicate the same trouble, then the problem is in your network. Your network may be flooding the Internet with data. If it is caused by a virus on a PC, find and eliminate the virus. If you are not sure which device is responsible for the traffic, systematically add each device back until the trouble returns. If it is caused by legitimate traffic, institute Quality of Service programming or traffic shaping in order to prioritize the voice traffic.

VoIP offers many benefits to consumers and businesses. However, it can experience voice quality problems because it is delivered on the Internet. With the use of a packet loss and delay test tool and a systematic approach of elimination, VoIP problems can be fixed and the benefits enjoyed with few if any hiccups.

This article was first publish on Technorati.

Voice prioritization is one of many areas that require a network administrator’s attention. Voice prioritization can be handled by the Differentiated Service Code Point (DSCP) field in the network’s packets or by segmenting VoIP equipment into a separate VLAN. This article discusses the set-up of VLANs for successful VoIP transmission.

VLANs have several advantages over using only the DSCP field, although they are somewhat more difficult to construct. They can effectively prioritize all of the mission critical VoIP traffic including call signaling. They will also exclude packets generated on computers that use the Expedited Forward (EF) Per Hop Behavior (PHB) of the DSCP field that may compete with mission critical VoIP. Additional advantages include the reduction of broadcast network traffic as well as higher security as other computers in other VLANs will not be able to monitor phone calls.

The network needs a managed Ethernet switch and an Internet router capable of manipulating the DSCP field to successfully implement a VLAN for voice prioritization. In addition, the computer and VoIP endpoint cannot share an IP address which means no softphones. The computer can use the small Ethernet switch on the back of most IP Telephones and share a single Ethernet cable back to the managed switch.

In setting up the VLAN, all computers and non-telephony devices are programmed as members of the default data VLAN. All VoIP telephones should be members of the voice VLAN.

The router is on the edge between the Local Area Network (LAN) and the Internet. Its LAN interface does know which packets are in which VLAN but its Wide Area Network (WAN) interface to the Internet does not. Thus, the edge router must set to ‘yes’ the EF bits of the DSCP field for all packets in the voice VLAN. It sets all the bits of the DSCP field to ‘no’ for all traffic in the default or data VLAN.

The edge router’s Quality of Service (QoS) capabilities should be enabled for traffic going out to the Internet on its WAN interface. Packets are sent to it with the EF field set to ‘yes’ for only those that were originally in the voice VLAN. The QoS settings recognize the EF field and prioritizes the voice packets out to the Internet.

For successful implementation of business VoIP services like Hosted PBX and Hosted VoIP, prioritization of voice packets out to the Internet is crucial. Of the two methods for establishing voice priority, VLANs require some extra hardware (managed Ethernet Switches) and a extra programming. However, they can do a superior job by including call signaling in the prioritization queues and excluding any non-mission critical traffic.

VoIP voice quality problems can have many causes. Missing or inadequate voice prioritization or QoS is a primary source of VoIP problems. This article provides some background on where QoS needs to be enforced in the network and gives an explanation on what needs to be done.

QoS provides priority to VoIP packets at network choke points. The most common network choke point, for most homes and businesses, is where the data traffic transitions from the Local Area Network (LAN) to the Internet. The LAN can be running at speeds of 10Mb to 100Mb (million bits per second) or more. DSL and cable Internet services may have speeds out to the Internet as low as 256Kb (thousand bits per second). In essence, the data is transitioning from a 10 lane superhighway to a 1 lane road. As VoIP is very sensitive to delays, it must not wait for its turn to enter the 1 lane road, your Internet connection.

QoS is put into effect by a router that examines each packet and ships specific ones to the head of the line. QoS can be accomplished through Virtual Local Area Networks (VLANs) or Differentiated Service Code Point (DSCP) inside the Type of Service field for IPv4 or Traffic Class Octet in IPv6. For those familiar with the 7 layers of the network, VLAN operates in layer 2 and DSCP is layer 3.

VLAN

A VLAN is a virtual subnet that creates smaller broadcast domains within the LAN to ensure efficient use of bandwidth. For example, your VoIP telephones can be grouped together in one VLAN and your computers into another. Separate voice and data VLANs can protect VoIP traffic from service disruptions caused by virus or worm activity because Ethernet switches may not bridge IP traffic between VLANs.

The data VLAN carrying general traffic to the Internet is given the lowest priority. The voice VLAN is given the highest priority.

DSCP

DSCP relies on packets being classified and marked as belonging to a specific class. DSCP aware routers implement Per Hop Behaviors (PHBs), which implement packet forwarding mechanisms with each class of traffic. DSCP is the primary protocol routers use to provide different levels of service.

Although a network can implement up to 64 different classes of traffic, certain encodings in the DSCP field are recommended. Most networks use the commonly defined PHBs of default, Expedited Forwarding (EF), Assured Forwarding (AF) and Class Selector. The EF PHB is for applications that require low delay, low jitter and low packet loss which makes it suitable for VoIP, video and other realtime services.

The primary disadvantage of DSCP is any application can mark the EF bit and compete with your network’s mission critical traffic. For example, your company may use a Virtual PBX instead of a traditional telephone system. Your calls to the Public Switched Telephone Network must transverse the Internet with low delay, jitter and packet loss. A router between the LAN and Internet gives packets marked with EF priority out to the Internet. Employees within your company may use personal Skype, Google Voice or other video services which may mark the EF bit as well and compete with your mission critical VoIP traffic. This problem is solved by certain routers that can inspect each packet and only keep the EF bit set for packets destined to specific IP addresses.

Although more difficult to implement, VLANs can provide superior voice prioritization if your computers and VoIP telephones are different devices. VLANs will prioritize all traffic within the subnet including call signaling. DSCP is easier to implement but is less accurate. However, smaller networks such as small businesses and homes, installing a router with DSCP traffic management is enough.

You can find it here http://www.hostmycalls.com/tools/.  This online tool is unlike most that just give you a brief result of the route, speed or ping latency.

To help you understand how the tool works, view this page Interpreting the Results of the HostMyCalls Packet Loss and Delay Test

If you find this free resource useful, you are welcome to link back to it on your site.  Linking code is available on the tool’s page.  Your comments are also welcome.

Don’t forget we do offer premium business grade Hosted PBX service! Click Sales Inquiry to find out how we can solve your communication needs.

Deployment problems manifest themselves with quality of voice issues.    Technical articles which offer advice on solving VoIP voice quality problems discuss jitter, latency and MOS scores.  You do not have to become a VoIP nerd to make a phone call.  This article shares the most common deployment issues that cause jitter, latency and poor MOS scores without ever discussing them.

Symptoms of mild voice quality problems consist of robotic, distorted or slightly choppy voice.  In most cases, all the words can still be understood.  Moderate problems are occasional broken words which have to be repeated.  Severe problems include frequently distorted and choppy voice, lost sentences and dropped phone calls.  If you are experiencing any of the problems, here is a short list of common causes:

1. Voice Prioritization.  Most Internet connections are though DSL or Cable.  These connections typically offer more bandwidth from the Internet (download) than to it (upload).  Because the upload speed is smaller, voice packets usually need to be prioritized going out to the Internet.  If you can hear the outside caller just fine but they have trouble hearing you, than this may be the problem.

Voice prioritization MUST be enforced between the cable or DSL modem and your LAN.  More and more routers include this ability and it is becoming easier for the average user to set-up, however, a VoIP professional may still be needed.

Any use of a DSL or cable modem integrated WiFi access point is likely bypassing your voice prioritization.  Further, you may experience Internet problems just by having your WiFi radio active in your modem when using your microwave or cordless telephone.  It is strongly recommended that you disable this feature in modems and use a separate WiFi access point whose traffic must pass through voice prioritization to get to the Internet.

2.  Poor Service from Internet Service Provider (ISP).  VoIP is very sensitive to problems in the Internet and many ISPs do not take care that they provide a reliable circuit.  ISP networks are comprised of many routers frequently called hops.  Each hop has a potential for network congestion which may be fine for normal data traffic but will cause problems for VoIP.

Other causes of poor ISP service are faulty DSL or cable modem, old outside cabling that has become susceptible to weather and router problems within ISP network.  Further, DSL service may be degraded by frequency interference in the providers cable bundle, load coils and bridge taps.

3.  Hubs and Ethernet Switches. Ethernet switches and hubs are the boxes that all of your data cabling connects to tie your computer devices together.  Your LAN cannot contain any hubs.  Instead Ethernet switches must be used, 100BaseT minimum.

4.  Multiple Chained Ethernet Switches.  Homes and offices with older wiring may use multiple Ethernet switches at desks, rooms and blocks of cubes to share single wiring drops back to the main LAN Ethernet switch.  Passing VoIP through multiple Ethernet switches to reach the Internet can cause problems.  Find ways to eliminate these extra devices through wireless access points and additional cabling.

5.  Insufficient Bandwidth for Number of VoIP Calls.  Without going into the dirty details of voice compression and codecs, you should in general have about 60kbps of upload bandwidth for every simultaneous voice call.  Insufficient bandwidth will choke your voice packets.

6.  Poor Wiring Inside Building before Cable or DSL Modem.  For DSL, each building or home has a DMARC (characterized by a wire block with orange cover) or Network Interface Box (homes).  The line carrying the DSL circuit should go straight from the DMARC to DSL filter and then DSL modem.  No other devices or connections should be in between.  Cable modems must work off of the primary splitter (not go through multiple splitters) and should be the leg with the highest decibel level.  When your cable repairman visits, he can verify.

7.  Other Applications May Prioritize Their Packets.  Any application can choose to use prioritization flags in their packets.  These applications may be in use with or without the network administrator’s knowledge including video and the myriad of consumer voice services such as Skype, Vonage, IMs, etc.  Assuming the use of these services is approved, your voice prioritization programming and Internet bandwidth needs to account for the extra bandwidth consumption.

These are 7 of the most common problems that may cause jitter, latency, poor MOS scores or just bad voice quality.  In some instances, you will need professionals to help with proper programming and problem detection.  Many tools exist as well.  If you believe all inside your house or building is in good shape, determining whether the problem is caused by your ISP can be difficult.

Most WiFi enabled access points operate in the 2.4 Ghz frequency range.  This unlicensed frequency range is also shared by many common household and business devices such as cordless telephones and microwave ovens.  Use of these devices within range of your wireless enabled ISP router can cause interference and other negative effects ranging from seemingly insignificant brief Internet outages up to the need for router resets.  Internet outages lasting only several milliseconds will be disruptive to VoIP calls using a Hosted PBX or Hosted VoIP provider.

If your ISP router is equipped for wireless networking service and is not being used on your network, I recommend the wireless feature be turned off.  Turning the wireless feature off eliminates the negative effects of any interference and a potential security risk to your network.

If your ISP router is equipped for wireless networking service and is in use on your network, it could be a source of negative voice quality issues as it bypasses the necessary quality of service (QOS) management for voice traffic.  Migrating wireless network devices to a separate wireless access controller is recommended.  Further, when you use a separate wireless access controller from your ISP router, interference from other devices in the same frequency range will have no effect on the operation of your Internet router.

For more information on how you can insure the best possible VoIP call quality from your Hosted PBX or Hosted VoIP providers, please read my other blog articles.  Please let me know your thoughts in the comments section below.