[asterisk-users] MagicJack and Skype call quality

[Julio Arruda]

Jason Aarons (US) wrote:
> My understanding is Skype's secret is using the iLBC codec, which Cisco
> has also licensed for their 79X2 models as well.  I travel and lot and
> in places where Yahoo Phone Out or MSN Phone or Cisco IP Communicator
> will fail the Skype client will work.  The iLBC codec can really handle
> packet loss.

AFAIK, not iLBC, but another GIPS codec.
ILBC is present in some grandstream phones from what I remember, not in 
the Cisco 7912 as one example, not sure about other phones.
In a word with still many PSTN gateways out there that don't support it, 
ILBC in the SIP UA side only can help that much :-)..

> 
> Skype High Quality Video with the Logitech Orbit AF on both ends is
> awesome. I got my family a set for Fathers day. Just amazing video
> quality. Uses a On2 VP-7 codec that has much lower cpu and other
> benefits over h.264.
> 
> 
> 
> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com
> [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Steve
> Underwood
> Sent: Saturday, July 12, 2008 3:30 AM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [asterisk-users] MagicJack quality
> 
> Tzafrir Cohen wrote:
>> On Sat, Jul 12, 2008 at 10:26:24AM +0800, Steve Underwood wrote:
>>   
>>> C. Savinovich wrote:
>>>     
>>>> I am puzzled by the quality of magicjack.  I keep trying to figure
> out how
>>>> they can the quality be that adequate.  Since Skype also has an
> excellent
>>>> quality, that leaves me to believe that software based calls
> (softphones)
>>>> could have and advantage over hardphones, provided there is a
> parameter that
>>>> those 2 companies are addressing.
>>>>
>>>> Anyone's thoughts on this?
>>>>
>>>> CS
>>>>   
>>>>       
>>> I don't know what Magic-jack does (I've never actually seen one), but
> I 
>>> know the key thing about Skype that impresses people - its wideband 
>>> voice codec. A lot of people poo-poo the idea that wideband voice has
> 
>>> value in a phone call. They are either close to deaf, or have never 
>>> tried it. Clarity is profoundly improved. Skype seems to use various 
>>> tricks to keep the packet flow smooth, but its wideband that makes it
> 
>>> sound better than the PSTN.
>>>
>>> You might think a standard phone plugged into an adaptor, like a 
>>> Magic-jack, would be limited to narrow band voice, as that is all the
> 
>>> phone was designed for. It turns out most phones only aggressively 
>>> filter at the low end of the band. They let a lot of energy above
> 4kHz 
>>> through, and they do generally sound better through a wideband codec.
>>>
>>> Many modern line interface chips are actually capable of running in a
> 
>>> 16k samples/second mode, even though most are programmed for 8k 
>>> samples/second. I think the ones on the TDM400P type cards can. Some 
>>> from Silicon Labs certainly can, and chips from Zarlink and others
> can.
>>>     
>> The DAA in those cards can work in 16Hz. So they can send higher
> quality
>> samples to the telco. Provided Zaptel supports it. But then again, it
>> will get lost as soon as it gets converted to digital at the telco,
>> right?
>>   
> I guess I wasn't clear. What I said was only useful for a SLIC to phone 
> connection. It won't be of any benefit for a DAA to PSTN exchange 
> connection, for the reason you state.
>> Anyway, the ProSLIC chip does not seem to support it. 
>>   
> Silicon Labs make a Wideband ProSLIC, Si 3216, which is, er, wideband. 
> As I said before, Zarlink and other make them too.
> 
> Regards,
> Steve