Benefits of The G.729 Codec When Using Open Source VoIP With VoIP Wholesale Providers

Many VoIP users have adopted an open sourcenetworks is often a choke point because the sending
solution such as Asterisk or SIPX to meet theirnetwork chooses the least cost path (which is often
international long distance calling needs. While thesealso the lowest quality path). This also means it is
open source software packages are cost effectivealways a good idea to use a low bitrate codec.
and very good at meeting the feature requirements of3. Among the low bitrate codecs available, G.729 has
most users, they suffer from one major drawback: thethe highest MOS (mean opinion score) at 3.9. MOS is a
inability to use the G.729 low bit rate codec.subjective rating given to voice codecs and runs a
Codec stands for Coder-Decoder. G.729 is a datascale from 1 to 5, with 1 being the worst and 5 being
compression algorithm (ie. codec) for voice thatthe best. A score of 4 and above is considered to be
significantly reduces the bandwidth requirements for a"toll quality" speech.
IP voice signal - from the standard payload size of4. Although there are other low bit rate codecs
64kbit/s down to 8 kbit/s. There are various versionsavailable for free (including G.723, GSM and iLBC) they
of G.729 (sometimes called G.729a, G.729b orare not widely supported or implemented by the
G.729ab) that further reduce the voice payload size tocarriers and service providers that must ultimately
6.4 kbit/s or less. Although G.729 is an ITU standard, itconnect your international call to the PSTN in the
is owned and licensed by a consortium of companiesdestination country. G.729 is the most widely used low
including Nokia, NTT, NEC, and France Telecombitrate codec and is universally supported by the major
(among others). Using the codec requires a licenseVoIP equipment manufacturers. For example, the
from Sipro or VoiceAge, companies that represent thefollowing text comes from one VoIP wholesale
owners (in the U.S.). The typical cost to license G.729 isprovider's support page:
US$10 per channel annually.Our carrier selection has been optimized for use with
Because of the licensing costs associated with thethe g.729 codec. If you set this as your first priority
G.729 intellectual property, it is impractical if notcodec, you will maximize your chances for completing
impossible for open source VoIP projects to supportcalls. That said, we use many underlying carriers for
this codec. This presents a problem for those usingtermination, and each carrier has different capabilities.
open source VoIP software to make international callsMany support g.711, but not all. The same goes for
for the following 4 reasons:g.723.1 and iLBC. As a result, if you set any of these
1. Although bandwidth may be cheap and plentiful incodecs as your preferred codec, a call may or may
most developed nations, it is not so readily available innot complete using it, depending on which of our
many parts of the world. This means that internationalunderlying carriers receives the call. Our softswitch will
VoIP calls made to these destinations may not haveallow your endpoint and the carriers to negotiate the
the 64kbit/s required by standard codecs. This meansmutually preferred codec.
it is always a good idea to use a low bitrate codec.For these reasons, it is the opinion of this author that
2. Even where bandwidth is available, the mediathe costs associated with implementing the G.729
packets sent for international calls must traverse manycodec are warranted in certain cases - namely when
different networks in going from point A to point B.using VoIP to make international long distance calls to a
The places where networks handoff traffic to otherVoIP wholesale provider.