Troubleshooting Voice over IP
Troubleshooting VoIP
Technology is wonderful . . . when it works. When it breaks, it can be a real pain. To ease the pain of problem moments, here are some steps you can take when things aren’t going well.
Local Issues
Always start with the most obvious.
Power – Are your local devices powered up? Do you see the indicator lights?
Internet Connection – Are the correct lights on your cable or DSL modem lit? Check your owner’s manual if you’re not sure. Usually there should be several lights on the modem. Power, Internet or WAN, Ethernet or LAN are most common.
Local Hardware – Are ALL your local devices powered up? Sometimes a power supply will fail suddenly with no signs of failure other than the fact that the device is no longer working. Check your cable or DSL modem, your ATA or SIP device and your router. Also check any other Ethernet devices you might have in the path to your han
dset like a switch or hub.
Phone Handset – Does your telephone handset work? Try plugging a different one into the same port. If it works, then the handset is the culprit.
Reboot – If everything is powered up, try rebooting the hardware in sequence starting with the cable or DSL modem. Wait one to two minutes before powering up each device. (This is a generic procedure. Sometimes a tech support person will know specifics about a specific piece of hardware that will cause them to give you a different instruction.)
Network Issues
The network between you and your VoIP service provider can sometimes be the source of problems. Your modem can be connected and showing all good indicators, but invisible network issues can still degrade the performance of your calls.
There is one DOS utility that can help you gather information that will suggest if your problem lies there.
Ping is a standard first-use tool for diagnosing network issues. Here’s how to do a basic test of your Internet connection.
Ping Yahoo.com
Click on the Start button, click Run and type cmd.
Then type ping yahoo.com and press enter.
You should see something like this:
C:UsersGreg>ping yahoo.com
Pinging yahoo.com [69.147.125.65] with 32 bytes of data:
Reply from 69.147.125.65: bytes=32 time=69ms TTL=49
Reply from 69.147.125.65: bytes=32 time=65ms TTL=49
Reply from 69.147.125.65: bytes=32 time=72ms TTL=49
Reply from 69.147.125.65: bytes=32 time=71ms TTL=49
Ping statistics for 69.147.125.65:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 65ms, Maximum = 72ms, Average = 69ms
The important information is the average round trip time and the (% loss) number. The time should not be over 100ms and the loss should be close to zero.
There are three primary network conditions that affect VoIP. These are latency, jitter and packet loss.
- Latency is the time it takes for a packet to travel from point A to point B.
- Jitter is the variation in latency over a series of packets.
- Loss is the number of packets sent from point A that never make it to point B
If the time is more than 100ms, you are experiencing significant latency. If there is significant packet loss (more than 1%), there is a problem with your Internet Service Provider. Contact them and tell them what you have seen. Sometimes they can solve the problem quickly.
SIP software or equipment
Some problems you may experience can be caused by the equipment in your office. Here are some things you may experience and suggestions about what to do or where to look.
Buzzing – A hum or buzzing in your earpiece can be caused by interference in your phone from electrical wires or transformers. Try moving the phone’s cables away from any electrical cords or chargers.
Make sure you have fully charged batteries in any cordless devices. When the batteries begin to weaken, the lower voltage they supply to the device electronics can cause unusual sounds.
Echo – Echoing in long distance calls is more common than in local calls, but it can happen at any time. Echo, and its close cousin, feedback, can sometimes be caused by speakerphone systems that are not correctly configured. Try turning the speaker volume down a little and see if things improve.
Two in-line technologies are used to fight echo in VoIP systems. They are called Echo Suppression and Echo Cancellation. If echoing is an ongoing problem for you, ask your technical people or VoIP hardware vendor if either of these technologies is part of your system, and if they are working correctly. Sometimes a hint helps.
There are instances where the use of a cheap analog telephone handset has been blamed for echoing audio. If you have any such devices in your office system, try disconnecting them.
Echoing can be caused on either end of a phone conversation. When both sides take measures to ensure correct installation, setup and use of the equipment, echoing problems can be avoided.
Firmware Updates – IP phones, VoIP routers and ATA’s are computing devices that work in an ever-changing system. If you are experiencing difficulties, check to see if your equipment is running the latest firmware. Sometimes this can make all the difference. Read your User Manual to find out how to check the firmware version, and compare that to the manufactures website, or contact the vendor of your phone equipment.
General Connection Problems
Public IP vs. Network Address Translation (NAT) – One issue that crops up in small business and residential networks is improper addressing. Your office network is a private network with its own addressing scheme that is distinct from the Internet. Devices inside your office network (on your side of the cable or DSL router) will nearly always have IP addresses assigned by your router. Those addresses are only good inside your office network.
One of the jobs your DSL or cable router does is routing packets of data from the Internet to each computer or IP-enabled device on your office network. If you cannot get your new VoIP equipment to work on your network, double-check the way you have it connected.
In most scenarios, the VoIP router or Analog Telephone Adapter (ATA) is placed in-line between the cable or DSL modem and the office network router. That way NAT translation occurs on the office side of the network, and the VoIP hardware is not involved in the NAT issue at all. The installation guide you received with your VoIP hardware should be followed carefully when setting up your new equipment.
Sudden Phone Death: Inner-Office Cabling Issues – One thing that is often overlooked is the simple data cable. If a phone was working, but now suddenly doesn’t work, or even worse works sporadically, replace the Ethernet cable with a new one. Damaged cables are common, especially if the phone gets moved for cleaning or stretched across the floor where people can trip or tug on it.
VoIP Service Provider (VSP)
There are some problems that you experience that are caused by problems at your VoIP service providers location. Here are a few:
Server Failure – Servers, the computers that handle your voice data, sometimes fail. Although your VSP most likely has gone to great lengths to prevent it, sometimes a server failure causes interruption of service. Most established VSP’s have redundancy built into their server systems to allow for instantaneous recovery from a server failure. Under normal circumstances, any failure of any single server should not be noticed by end-users.
Power Outages – If local power goes down at the site of your VSP’s server farm (that building where all those computers and equipment are located), it bring the whole system to a halt. Not only does a power outage cause loss of communication, but data corruption can occur, making your voicemail or your online fax documents unusable.
Most established VSP’s have backup power generators and uninterruptable power supplies (UPS’s) installed to prevent loss of power for even a millisecond. However, not every provider goes to this expense, something to keep in mind as you are selecting a provider.
VSP <> Carrier Issues – Occasionally someone will fail to pay their bills. If your VSP suddenly disappears, it could be they are having trouble negotiating their service agreement with the carrier who owns the actual lines your data is flowing through. Choose your VSP carefully. Cheaper isn’t always better.