& VoIP Telephone Service Checklist
Check these things work before you drop the Phone Company...
If you have ADSL from your Phone Company, you probably need to
keep a phone line. Some DSL providers will now put ADSL on a
dedicated pair (where you don't need a phone line), called Dry or Bare ADSL. If your broadband
connection isn't reliable, your VoIP phone service won't be
The more bandwidth you have in each direction the better for VoIP.
If you can get SDSL (Synchronous DSL), where the speed is the same for both
downloading and uploading, that would be good (harder to get, and
usually more expensive).
A real data T1 would be 1,500K both up
and down, which is as good as you can get - but if you fill up
that pipe with music or video downloads etc., your calls will
still sound bad.
Get a separate broadband (SDSL or T1) connection just
for voice if you're planning to use VoIP lines. It will save a
lot of grief later. Having two totally separate CAT5/6 networks in
your office, one for VoIP and one for data, can make sense. If your
computer network already seems slow on your PCs, you're not going to
be happy putting VoIP on that same network!
You may hear the term QoS (Quality of Service) thrown around. The
idea is that you give voice packets priority over all other types of
packets. If your VoIP calls sound bad because your broadband pipe to
the Internet is full (either up or down, although QoS is usually
only applied to packets going up to the Internet) QoS won't do
anything. Even after spending a lot of money to implement QoS. A
dedicated broadband connection sized properly for your traffic is
the only answer to getting good sounding VoIP calls.
Bandwidth is the most important component of any VoIP telephone
service. We've all heard calls that are garbled or choppy, and
it's always because of a bandwidth or latency
(delay) issues (either on
the local network or somewhere on the Internet).
With most VoIP providers you need about 128K for each VoIP
telephone line, in both directions. If you have four lines,
you need 512K both upload and download. Most ADSL lines are very
fast downloading, maybe 1,500K, but they limit the upload speed to
maybe 384K. That means that even if you aren't uploading stuff from a PC
to the Internet while you're talking, you don't have enough
bandwidth to have four people talking at the same time - you'd
need at least 512K upload speed. In this case, you'd probably hear
the other people OK (with your 1,500K download speed) but they'd
have a hard time understanding you (it would sound garbled).
On some broadband connections, like Cable, your connection speed
will be reduced when a lot of other people in the neighborhood are
using their Cable Modems, so your voice calls will sound worse
during that time. If you use a computer on the
Internet at the same time, things will really get garbled from
time to time. If you have a 1,500K T1, and the company selling you
the T1 only has two T1s feeding the neighborhood with 20 customers
(3,000K), if other users are downloading stuff totaling 2,500K
that only leaves 500K of bandwidth for your VoIP
calls - even if you're paying for a whole T1. Probably OK at a home, but it doesn't give a good
impression at a business.
You would have the same issues
using a Hosted PBX, where you use electronic VoIP telephones with
buttons and a display connected to your office Ethernet network.
These phones "talk" to a PBX located somewhere else in
the city (or world... but closer is always better).
A Hosted PBX will
give you more features that are easier to use than with a standard
single line analog phone, without your having to buy a phone
system at all. Problems arise from the fact that all of the signaling
and voice packets have to travel through your office, through your
ISP (Internet Service Provider), and through the public Internet to the
Hosted PBX service provider.
If you have a lot of phones at your main office, a Hosted PBX
probably won't work since with only ten users you'd need 1280K out
of a full 1500K T1 for the calls to sound decent (128K x 10),
leaving you only 200K for all your email and Internet use if all 10
users are on the phone. If you don't have a lot of
off-site workers, having the PBX at your office (not Hosted) makes
the most sense, since only workers off-site will be using up
bandwidth on your T1.
Having a separate T1 or DSL connection for VoIP calls usually makes
a lot of sense.
With enough users a T3 (the same bandwidth as 28 T1s) might be
necessary. They're not cheap (but getting cheaper). They're just a cost of doing business
if you want to have a lot of people on VoIP at one location
(especially with a Hosted VoIP PBX).
There is no question that you'll have
intermittent problems with VoIP call quality if you put your
Internet and VoIP traffic on the same broadband connection, unless
you have A LOT more bandwidth than you'll need.
- Number Portability
It's OK to port a real phone number to the VoIP
company but you won't be
able to take the VoIP phone company's number to another phone
company (don't give out any numbers the VoIP provider gives you - ever).
Most VoIP providers "rent" the numbers from another
company, so the numbers aren't theirs to give you.
If a company other than a real
phone company or LEC (Local Exchange Carrier) tells you that you
can keep their phone number forever, don't believe it. You
may be able to port a number you get from a VoIP provider
today, but that could easily change next week.
most CLECs (Competitive Local Exchange Carriers) and VoIP
companies "rent" their numbers from other companies, if
the company who actually owns the number decides to exit the
business for one reason or another and the number can't be ported
for one reason or another, the number is lost forever - not
Always get your phone number from a real phone
company (LEC or ILEC - Incumbent Local Exchange Carrier), like
Verizon, Quest, AT&T, etc. Then port it to the CLEC or VoIP
company of choice once it's in and working (the LEC could still
take it away from you, but that's very rare).
If you need an 800 number get it from a real 800 number provider
(usually a long distance provider), who will "forward" every call to
that 800 number to your real phone line or VoIP line.
It's possible that an 800 number gotten from an 800 number
provider could be taken from
you, but that's rare. Because the 800 number service
provider owns the 800 number, not you, it's possible
for someone to hijack the 800 number and for you to lose it (by
mistake or on purpose).
The independent 800 number provider can simply change where the 800
number is forwarded to whenever you need it changed. They are
totally separate from your local or VoIP phone service, and they
don't care where you point the 800 number to.
Never get your 800 number from a VoIP provider. There is
little chance that you'll be able to keep it if you change VoIP
providers. If you never give anybody the 800 number and only use it
internally, getting an 800 number from a VoIP provider that you'll
probably lose at some point is fine.
None of this stuff works without power, unlike a real phone
line. None of it takes a lot of power, so a good sized battery
backup from the computer store will probably keep stuff going for
quite a while (if the batteries are good, but most batteries go bad
couple of years... which you find out during a power failure).
- Alarm System
It probably won't work on a VoIP line without some changes.
Although some VoIP providers tell you to simply plug their VoIP
device into the nearest jack, after disconnecting the Phone
Company's line where it comes into the building, the alarm won't
work that way (it probably uses an RJ-31X to isolate the phones from
the phone line, so the alarm system can dial out even if the phone
line was in-use). Coordinate VoIP with your alarm company!
The reason burglar or fire alarms probably won't work dependably is that the alarm is using tones to
communicate, like a modem or sometimes like a touchtone phone. VoIP
lines are designed for voice, compressing the sounds as much as
possible. When you compress modem tones or other tones or break them
up into small packets, they often
just don't make it to the other end so that equipment can understand
Your alarm company may be able to hook up your alarm system so
it transmits on the Internet instead of a phone line, but that
doesn't make much sense since there's a good chance the Internet
won't work when the alarm goes off (Murphy's Law).
Keep a real phone line for your burglar or
- Ground Start Trunks
Some PBXs are setup to use Ground Start Trunks. A Ground Start
Trunk is dead for outgoing calls until the phone system puts ground
on the phone line (the ring side) for maybe a quarter second. Ground
Start trunks are thought to help reduce "glare," where someone is
trying to make an outbound call and actually gets a new incoming
call because the trunks are all pretty busy.
Most VoIP boxes and cable company boxes only offer Loop Start
Trunks, where all it takes to get dial tone is to go off-hook. Even
if the VoIP box or cable box can be optioned to provide a Ground
Start Trunk, the provider probably doesn't know what a Ground Start
Some older phone system required a different trunk card for a Ground
Start or Loop Start Trunk (a lot of hotels still use these systems). Some have jumpers or programming options
for Ground Start/Loop Start. In any case, if your system requires a
Ground Start Trunk and you give it a Loop Start Trunk, you won't
be able to call out, incoming calls may or may not ring, all the
lines may be busied out so no lines work at all, and you may get
phantom ringing (incoming calls with nobody there).
- Special Handsets
Many factories, restaurants and even some offices are pretty
noisy. Your company may have amplified and noise cancelling handsets
on your existing phones, and maybe even Push to Talk (PTT) or Push
to Mute (PTM) handsets on some extensions.
Most of the VoIP phone system manufacturers try to make the
"hippest" looking phones (and handsets) they can. Instead of
the handset being the size and
shape of a "normal" handset (as originally designed by Bell Labs),
it may be an odd shape and very tiny so there's no room in
them for anything special. And other types of phones won't hang-up
in the handset recess on the phone.
If you have a noisy area and you can't get noise cancelling handsets
for your new phone system, you'll likely never live it down.
Check all your phones before signing on the dotted line to see if
you're forgetting something critical!
The military requires PTT handsets in many sensitive areas. That's
so the person on the other end of the line can't overhear other
conversations in the area as the background to a conversation, and
so that if the handset is laid down on the desk the person on the
other end won't hear all the conversations in the room.
If people are used to dialing 911 to get the police, and it
doesn't work, it could be bad. Most VoIP providers give you
stickers to put on the phone that say "911 might not
work." Write the local non-emergency number on the sticker.
- Telephone Book Listings
You may or may not be listed in the white or yellow pages, or
I don't know if this works, but there's a free service that will
help you get listed in real phone books:
- Caller ID Displayed
The name and/or number that people see
on their Caller ID box when you call them may not be yours, and it
may even say Cellular Call, Out-of-Area or Unavailable when you call someone
(depending on who the VoIP provider rents their numbers from).
If all of that VoIP provider's calls go out with a single Caller ID,
and a telemarketer or other type of bad guy is also using that VoIP
service, you'll develop a very bad reputation when people lookup
your Caller ID on google.
As of this writing Skype shows the same Caller ID for all its
outbound calls if you don't "rent" a phone number from them. Lots of
scammers use Skype, and you could be thrown in with them if you use
a service with a generic Caller ID.
- VoIP Voice Mail
Some VoIP providers force your calls to go to their Voice Mail
if they aren't answered in X rings. If you don't want to use their
voice mail, that can be a problem.
- Network Down Option
Most VoIP providers will
automatically forward calls to the number of your choice if their
main system can't communicate with your VoIP device. This is
critical: Put your cell
or some other number in that field!
Read the SLA (Service Level Agreement) carefully for any service you
decide to use for incoming calls. Keep in mind that 99%
uptime means your phone number won't work for
over 7 hours out of the month. A 99.99% uptime
means that your phone number won't work for over
4 minutes a month.
The uptime numbers probably won't include intended
downtime for maintenance of the servers or routers at
the VoIP provider's data center, normally done in the middle of the
night. That could add an hour or more of downtime a month (which you
never see on a phone line / voice T1 from the real phone
If you're just using VoIP for outbound, getting cut-off once in a
while or not being able to make outbound calls once in a while isn't
a big deal (especially when you consider the savings over real phone
lines). Not being able to receive incoming calls could cost you a
lot more than the savings.
Here is an example SLA from a business VoIP provider:
XXX Company will credit its customers with a half of the month's
charges for down-time caused by failure of it's server/switch that
exceeds three hours in any month.
VoIP has some inherent risks with interruptions of bandwidth and
Customer Premise Equipment (CPE), like routers and ATAs, so
naturally this is not covered. You should have confidence in our
server/switch, and we back it up.
Works OK with some VoIP providers (you may need a
Won't go through 100% of the time, but most fax machines try
three times before giving up.
The reason faxes won't work
is that the fax is using tones to communicate, like a modem. VoIP
lines are designed for voice, compressing the sounds as much as
possible. When you compress fax tones or break them up into small
packets, they often just don't make it
to the other end so that equipment can understand them.
Might work at slower speeds? Probably not.
The reason modems won't work
is that the modem is using tones to communicate. VoIP lines are
designed for voice, compressing the sounds as much as possible. When
you compress modem tones or break them up into small packets, they often just don't make it to the other
end so that equipment can understand them.
Credit Card Machines
They don't use fast modems. They may not work on
VoIP lines. They're just transmitting tones to communicate.
If you have a store you can use Internet type credit card machines,
but keep a couple of regular phone line credit card machines around
along with a real phone line or two so you'll be able to keep
selling when the Internet is down.
TV Set-Top Boxes
Some cable or satellite set-top boxes have an option in
programming to make it work with VoIP. Probably won't work without
your changing something.
Water, Gas or Electric Meters
Some utilities have spent big bucks to install modems on their
meters so they can read them remotely. There's some chance that
the modem won't work with a VoIP line. When your utilities are
shut off, you'll know for sure.
Sometimes you just can't get rid of it. It depends what's
causing it (see our
Echo Tech Bulletin below).
Incoming DTMF Digit Recognition
Sometimes Automated Attendants or Voice Mail Systems don't
recognize DTMF digits over VoIP lines when people call in, usually intermittently.
Talk-off (Outgoing DTMF from an
Analog adapter - ATA)
Some people's voices have components of the two frequencies
that make up a particular DTMF (touch tone) digit.
On a Voice Mail system, talk-off usually causes the system to stop
taking a message when the person leaving the message is still
On an analog VoIP adapter (ATA), especially the Linksys SPA-XXXX
series, talk-off causes random DTMF digits to be sent from the ATA
end, which are only heard by the person on the other end of the
call. This can be fixed by changing the DTMF type in the ATA from
RFC2833 to INBAND in the ATA, but can result in DTMF digits not
being understood when calling a voice mail or IVR system (like
Talk-off is not a problem from electronic VoIP phones since DTMF signaling is
always done by actually pushing a button on the VoIP phone, which
sends a packet of information to the other end (it doesn't have to
listen for the DTMF audio from an analog phone's dial, which can be
imitated by some people's voices).
Automated Attendant or Voice Mail
Some analog VoIP devices don't send a disconnect signal (like the
real Phone Company usually sends). That means that when the
outside party hangs-up after leaving a message, there may be a lot
of silence or busy signals at the end of the Voice Mail message.
Likewise, if someone calls in and hangs-up before making a
selection on the Automated Attendant, the now disconnected call
will end up ringing the phone programmed to get calls if someone
just "waits" and doesn't dial an extension number
(doesn't make the real person answering the phones very happy).
Many companies solve that problem by disabling 0 (the operator)
entirely. Screw the customer.
Paging / PA System
May or may not work with a particular VoIP phone system or
Has a similar problem as noted above with Automated Attendants with
disconnecting when the person is done paging (without a loud busy
signal or whatever coming over the speakers for a while).
Door Entry Systems
May or may not work with a particular VoIP phone system or Hosted
Some analog VoIP devices will only ring a single phone. The real phone
company provides 5 REN worth of ringing. Most VoIP devices provide
less. Many provide under 75VAC, which is the minimum a phone
company is supposed to supply (VoIP companies aren't really phone
companies - even though they claim to be, so they don't have to
adhere to any standards). A
Ring Voltage Booster is available.
Test it before you commit. Test it at different times of the
day, and with different loads on your own network. Even if it
sounds good to you, call many people and ask them
how you sound. The VoIP providers think if the other party sounds
good to you, you'll think their service is great. In reality, you
may sound garbled to the other party and it may be at a low
volume. Where you put the VoIP device on your network may make a
A phone that connects with a USB or sound card connection (screen
phone) will be very dependent on what you're doing
on that particular PC. It would be best to do nothing while you're
on a call going through a PC.
When you test the VoIP quality be sure to have someone call
you from that line when you're on a regular phone line. Most VoIP
service providers have learned that if they make the call sound OK
to the person using the line locally, their service won't be
cancelled for quality issues as quickly. In many cases, they tilt
the bandwidth (or the customer is using ADSL where the outgoing
bandwidth is limited anyway) so that the call sounds fine to the local caller
while it's garbled or choppy to the person on the other end. Try
it many times, at different times of the day, before deciding
whether to keep the service (most offer a 30 day moneyback deal of
one kind or another).
There's a hiss, or background white noise on some VoIP lines/ATAs.
Sometimes it's there all the time, sometimes just on some calls.
Listening to the background noise on these calls is very tiring if
you have to be on the phone all day.
Drop-outs / Cut-offs
Test it before you commit. Test it at different times of the
day. It's often worse at different times of the day depending on
your type of Internet connection (T1, DSL, cable, etc.) and the
general traffic at your ISP / on the Internet. If there are a lot of
people watching/downloading movies in your neighborhood at the same
time, VoIP could become very garbled.
Test it for at least a month or two. A VoIP provider
(of lines or a Hosted PBX) could go down quite a bit. You won't know
in a day or two of testing, but a couple of months will give you an
idea of what to expect. Whatever the test costs you could save you a
lot of money and grief in the long run.
If you're planning to use VoIP between two locations (like an office
and branch office or home worker), consider using a VPN (Virtual
Private Network). A VPN will encrypt the SIP (VoIP) packets that
carry the conversation (and any other data you send like email and
spreadsheets, etc.). That encrypted connection is called a VPN
VPN routers are inexpensive and pretty easy to setup these days. You'll
need one for each end of the connection.
One reason to encrypt your VoIP traffic is to prevent your ISP from
blocking/degrading the quality of VoIP calls by messing with the SIP
packets, which are easy to identify as they go through their
routers. Why would they do that? Because they probably are or
own a phone company in addition to offering broadband. If
your VoIP sounds terrible you're more likely to switch to their
phone service (which is almost always a better quality than VoIP,
even if they call it VoIP themselves).
Delay After Dialing
Some VoIP providers have a long delay after the last digit
dialed before your call goes through. That can sometimes be fixed
by adjusting the number of digits they're expecting (called the "dial plan"). Sometimes
their service is just screwed up at different times of the day. Sometimes a particular VoIP phone might
require that you hit * or # after your number to start dialing
(that's a pain!).
Before committing, call or email VoIP customer service a few times to see if
you can live with that level of support.
What happens if you don't like
the VoIP service after a while?
It's better to think about this now, rather than when it
happens. Paying an extra fee to drop the service before the
contract is up isn't that bad. Making sure now that you can get
phone service from another vendor is important.
What happens if the VoIP company
goes out of business?
It's better to think about this now, rather than when it
happens. You can hear a couple of stories in our
Think About Before Ordering VoIP
The reality of the economy is that if you're reading this you've
already decided to switch to VoIP to some extent to save money. You
may not consider my suggestions of things to check out first, but at
least when something doesn't work to your expectations you'll have
an idea of why... because you've already read about it.
to check out Things
to Think About Before Ordering VoIP for a much more detailed list
of CLEC, Cable and VoIP phone line quirks
If you're having echo problems,
click HERE to read our
Echo & DTMF Problem
Click HERE to see
the July 2014 Tech Blog on making VoIP sound perfect