|
1. How much
bandwidth do I need?
2. How do I
dial an International phone number?
3.
Why does my
call sound broken up?
4. Does the
system support IP to PSTN faxing?
5.
Can I use
this service with a Satellite Internet
connection?
6. What does
an error 205 mean?
7.
What does an
Error 104 mean?
8. Does the
system support IP to IP faxing?
9. What
value should I set my Registration Interval to?
10.
What does
"PSTN" mean?
1. Your connection speed
(bandwidth) must be sufficiently high for the
type of vocal codec you are using. Vocal codecs
(or just "codec") are the standard means by
which your IP Phone (UA) encodes your voice and
transmits it across the Internet. The codec that
is picked for a particular phone call is
primarily determined by your UA's configured
preferences. Consult your UA's manual to
determine how to change codec preferences.
To use the best quality / highest bandwidth
codecs (G711a/u) we recommend a connection speed
of no less than 90Kb/s in each direction (up and
down).
2. To dial any PSTN phone number
that is outside of the NANP (North American
Numbering Plan), you must dial:
011 + Country Code + City Code + Phone number
3. This can be caused by a
variety of problems. The most common is poor
Internet connection quality or lack of
bandwidth.
Very often what is sold as a "High Speed" or
"Broadband" connection is not up to the task of
transmitting voice packets in a timely or
reliable manner. Problems such as high latentcy
(slow delivery of packets) or packet loss
(actual dropping of voice data) can be seen from
time to time on some provider's networks. These
problems will be heard by you on your IP phone
call long before they are noticed for other data
activities like checking email or web browsing.
To track down where the problem is coming from,
you can use packet tracing software to reveal
network bottlenecks and get them reported to
your ISP. We recommend a product called "Ping
Plotter". You can download a free trial version
at
http://www.pingplotter.com
4. IP to PSTN faxing is not
supported.
5. In general, we do not
recommend the use of our system over a Satellite
(SAT) Internet connection. However, some
customers do. There are a few technical issues
related to SAT links that can cause problems:
- Round Trip Time (RTT) Delay. Most SAT's used
for Internet connections are geosynchronous.
This means that their orbit period is the same
as the length of a day, so they are stationary
in relationship to a given point on the ground.
To achieve such an orbit, the SAT must be 22,235
miles (35,784 km) above the earth's surface.
Radio waves travel at the speed of light, but
even the speed of light takes a noticeable
amount of time to travel that distance 4 times
(up and back twice for a complete round trip
from your UA to our servers.) This delay, when
added to other factors on the ground, can cause
delays anywhere from 500 ms to 1000 ms (1/2
second to 1 second.) It can be very difficult to
carry on a conversation when there is that much
delay.
- Network Jitter. Probably more important than
RTT Delay itself is the consistency (or lack of)
of the RTT Delay. Some packets take longer than
others to reach their destination which can
cause voice data to arrive out of order and
possibly be dropped. We have found that many SAT
Internet connections have this failing. Many
UA's have adaptive Jitter Buffers which can
absorb some small inconsistencies in RTT delay,
but given large inconsistencies, the result is
often an almost unusable connection.
- Lack of uplink bandwidth. Typically SAT
Internet connections are asymmetrical with their
download bandwidth being much higher than their
upload bandwidth. If your uplink bandwidth is
lower than the bandwidth required by the vocal
codec you are using (see the Knowledge Base
article on Codecs), then you will not be able to
use the connection for voice calls reliably.
6. The system has detected a
PSTN call from an IP Phone (UA) that is not
registered correctly. To prevent abuse, all UA's
must register with our proxy server before they
can place a PSTN call. Common reasons for your
UA not to be registered are:
PROBLEM: Incorrectly set USERID (phone number)
or PASSWORD in the UA
SOLUTION: Make sure your USERID and PASSWORD are
set correctly. Re-enter them if necessary.
PROBLEM: "Registration" is set to "Never" or
"No" in the UA's configuration
SOLUTION: Modify your UA's configuration to
force it to register before placing a call.
PROBLEM: Call placed too soon after registration
SOLUTION: Wait at least 5 seconds after
successful registration before making a PSTN
call.
7. The
problem is that the system has detected more
than one IP Phone (UA) registered with a phone
number that is associated with an unlimited
calling plan. Calling plans are restricted for
use by only a single UA to prevent abuse. The
simple solution is to make sure that you only
have one UA programmed with the virtual phone
number that is associated with your calling
plan.
Occasionally, due to power outages or UA reboots
more than one registration can appear for the
same UA, triggering an error 104. The old
registration will eventually expire (you can
check for when on your control panel.)
This FAX service is
not guaranteed.
IP to IP faxing, both the sender and receiver
need to be Dialwave members and have their fax
machines attached to IP analog telephone
adapters (ATAs).
One other important factor when faxing over VoIP
is the quality and speed of your Internet
connection. Since fax data cannot be compressed,
the G711u/a CODEC must be used. This codec
requires a minumum of 64Kb/s in both directions
to be reliable, but we recommend more than
90Kb/s.
9. Registration is the event
where your IP Phone (UA) contacts our system and
tells it where you can be reached for incomming
calls. The registration interval is the time
(measured in minutes or seconds) between when
your UA re-registers. Registration is required
before you can make PSTN calls (see the
Knowledge Base article on Error 205.)
Our sip proxy forces a 60 minute registration
regardless of the interval specified in your
VoIP adapter.
10. PSTN is an acronym for
Public Switched Telephone Network. It is the
traditional telephone system that the world has
been using for decades to make phone calls. In
order to access the PSTN from your IP Phone (UA),
you need to use a "bridge" between VoIP and PSTN.
This is accomplished seamlessly by dialing a 1 +
areacode + phone number for a North American
call or 011 + country code + city code + phone
number for an International call.
|
