Does a VoIP call sound as good as an ordinary call?

VoIP calls often have better quality than ordinary phone calls, if you received a call from someone who was calling from a good quality VoIP service it’s unlikely that you would notice any difference from an ordinary call.

However, VoIP call quality depends upon the telephone used to make the call, the callers broadband connection and the Internet Telephony Service Provider who carries the call.

What are the most common problems that I may encounter using VoIP?

As VoIP requires an Internet connection to your premises, the most common problems are to do with:

• Initial firewall settings to allow VoIP traffic in as well as out
• Your broadband needs to be able to handle the number of concurrent calls you want to make
• Audio problems can emerge if your broadband service is reduced for any reason, or if your data traffic increases. DSL routers with QoS (Quality of Service) can ensure that voice takes precedence over other Internet traffic

Troubleshooting Audio Problems

VoIP Audio problems can be split into two sections:

• New Installations
•  Existing Installations

For new installations, audio problems (choppy speech, one way audio, etc.) are usually caused by, lack of bandwidth, router, firewall, or network settings:

• Check that your router, firewall and other network equipment has the latest firmware
• Run a speed test (www.speedtest.net) to confirm your broadband download and upload speeds
• Then check that the firewall will let VoIP traffic in, as per your ITSP recommendations

For existing installations where voice quality was good, but has deteriorated:

• Has your broadband service changed?
• Are you making more concurrent calls?
• Has anything changed on your network?
• Reboot your DSL Router and IP Phones?

Troubleshooting Static or Garbled Audio Problems

Static or buzzing on calls is usually due to interference from other electronic devices. Move other electronic devices away from DSL Routers, Switches and phones to see if this reduces static.

Garbled or choppy audio is the result of latency or packet loss on your Internet connection. Your connection may not be fast enough to send and receive voice data, resulting in lost information. This situation is called “Packet Loss”.

• Check the speed of your Internet connection, is there enough bandwidth for the number of concurrent calls you are making
• Is other data being sent or received over your Internet connection?
• Does your DSL Router support (QoS) to ensure that VoIP data takes precedence over other internet traffic?

Troubleshooting Echo Problems

Echo is due to possible latency on your Internet connection causing delayed playback of your voice. It is not uncommon for echo to be present with traditional phone calling as well, but the latency is so slight the echo probably will go unnoticed.

Possible causes of echo are:

• Poor quality telephone or phone cables (possibly on the far end of the call)
• Feedback between the phone’s speaker and microphone, try turning the microphone down

If you are hearing significant echo on a call:

• Try to call back the number and see if the echo persists
• Ask if the person you are talking with can use a different phone
• Check a few websites you commonly view and see if they are performing slower than usual. If this is the case, it is probable that your ISP is experiencing a problem
• If anyone is sharing your Internet connection, or you are uploading/downloading files via the Internet, pause this activity and see if voice quality improves

Troubleshooting Incoming Call Problems

Inbound call problems are usually due to your Internet phone not being registered with your ITSP or a problem with your Internet.

• Can you browse the Internet and view web pages, like www.commscouncil.uk? If not, reinstate your Internet service and re-try
• Does your Internet telephone have a dial tone? If not, check the power and network connection
• Check to see if your router has a firewall that is blocking inbound VoIP data
• If you can browse the Internet and your phone has a dial tone, then restart your Internet router and your Internet phone
• If problem persists, contact your ITSP

Troubleshooting Outgoing Call Problems

Outgoing call problems are usually due to an Internet fault on your premises

• Can you browse the Internet and view web pages, like www.commscouncil.uk? If not, reinstate your Internet service and re-try
• Does your Internet telephone have a dial tone? If not, check the power and network connection
• If you can browse the Internet and your phone has a dial tone, then restart your Internet router and your Internet phone
• If problem persists, contact your ITSP

What type of Internet connection and bandwidth is required to ensure good voice quality?

To make and receive VoIP calls you need a high speed broadband Internet connection, the speed or bandwidth you require depends upon how many concurrent calls will be made and what codec your Internet telephone will use to digitise speech.

You will need at least 80kbps on both the upload and download for a single two-way conversation using the G711 codec. The data rate for the G711 codec is 64kbps, but added to this will be headers and other information, adding up to an approximate total of 80kbps. Other codecs use higher compression ratios and can be used with lower bandwidth, like G729 and others.

So for 10 concurrent calls using G711 you will need at least 800kbps broadband upload speed.

What are the potential security risks when using VoIP?

VoIP vulnerabilities are typically similar to the ones users face on the Internet, although some attacks unique to IP telephony are now emerging.
Specific vulnerabilities that can be exploited range from:
Criminal (fraud) e.g. Vishing, Caller ID Spoofing
Malicious disruption e.g. DOS attacks
Unsolicited calls e.g. SPAM over Internet Telephony (“SPIT”).

Are there more risks to a VoIP service than a traditional phone service?

All new or emerging technologies offer both opportunities and vulnerabilities, particularly if the scale of their adoption is potentially enormous.

Many of the motivations to attack VoIP users are the same as telephone service attacks: to benefit financially, via toll fraud, identity and information theft, and to gain notoriety, by disrupting service and inconveniencing users. Such attacks are similar to attacks we have seen on cellular and landline phones for years.

Others are all too familiar attacks we see against networked computers. VoIP phones and computers running VoIP software (softphones) are more computer than phone. They have operating and file systems, use Internet protocols, and run data and management as well as voice applications. They are vulnerable to unauthorized access, privilege escalation and “system” misuse. Viruses, worms, and all the “classic” denial of service attacks that exploit network protocols are possible.

What is a Denial-of-Service attack?

A Denial-of-Service attack (DoS attack) is an attempt to make a computer resource unavailable to its intended users. Although the means to carry out, motives for, and targets of a DoS attack may vary, it generally consists of the concerted efforts of a person or people to prevent an Internet site or Web service from functioning efficiently or at all, temporarily or indefinitely. Perpetrators of DoS attacks typically target sites or services hosted on high-profile web servers such as banks, credit card payment gateways, and even root nameservers.

In terms of VoIP telephony, DoS attacks can overwhelm a company’s phone lines, creating long-term busy signals, forcing calls to disconnect.

What is SPIT?

SPIT or SPAM over Internet Telephony is the proliferation of unwanted, automatically-dialled, pre-recorded phone calls using VoIP. VoIP systems, like email and other Internet applications, are susceptible to abuse by malicious parties who initiate unsolicited and unwanted communications. Telemarketers, prank calls and other telephone system abusers are likely to target VoIP systems increasingly.

Up to now there have not been a great many instances of VoIP spam but there is great potential for it to become a major problem. SPIT could be generated in a similar way to email spam with botnets targeting millions of VoIP users from compromised machines.
The real-time nature of voice calls will make dealing with spit much more challenging than email spam. While emails can sit on a server to go through a spam filter, calls need to be filtered/detected in a real-time environment.

What is Vishing?

Vishing is the criminal practice of using social engineering over the telephone system, to gain access to private, personal and financial information from the public for the purpose of financial reward. The term is a combination of “voice” and phishing. Vishing exploits the public’s trust in landline telephone services, which have traditionally terminated in physical locations which are known to the telephone company, and associated with a bill-payer. Vishing is typically used to steal credit card numbers or other information used in identity theft schemes from individuals.

(Social engineering is the act of manipulating people into performing actions or divulging confidential information)

What is Caller ID spoofing?

Caller ID spoofing is the practice of causing the telephone network to display a number on the recipient’s caller ID display which is not that of the actual originating station; the term is commonly used to describe situations in which the motivation is considered malicious by the speaker. Just as e-mail spoofing can make it appear that a message came from any e-mail address the sender chooses, caller ID spoofing can make a call appear to have come from any phone number the caller wishes. Because of the high trust people have tended to have in the caller ID system, spoofing can call the system’s value into question.

For example, an attacker could possibly inject a bogus caller ID into an ordinary VoIP call so that the receiver believes the call to be coming from a known and trusted source (a bank, for example). The receiver, fooled by the electronic identification of the caller, may place unwarranted trust in the person at the other end. In such an exchange, the receiver may be tricked into disclosing personal information like account numbers, social security numbers, or secondary authentication factor: a mother’s maiden name, for example. This scheme is essentially the VoIP version of traditional phishing, where a user follows links in an unsolicited email and is tricked into providing personal information on a bogus website. Attackers may use these bits and pieces of personal information to complete partial identity records of victims of identity theft.

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