[asterisk-users] iax vs. sip?

Rich Adamson radamson at routers.com
Thu Aug 31 07:15:15 MST 2006


We've been using iax with teliax.com for a couple of years, and it seems 
the quality of calls varies with time. Sometimes it is good and next 
time its not so good. There has been changes occurring to iax and the 
jitterbuffer stuff over the last two years, and I'm reasonably certain 
that some poor quality is related to differences between teliax.com's 
implementation (eg, s/w versions) and ours. I've not bother to try sip 
since our asterisk implementation is truly both a production box for our 
small office, and a test box for various version testing, etc.

> We used iax for more than a year and moved to sip about 6 months ago.  
> The quality from termination providers seems much better now with sip.
> 
> Tom
> 
> At 09:38 PM 8/30/2006, you wrote:
>>
>> I have no NAT issues.  My PBX is multihomed and the outside IP is 
>> locked down for all except IAX and SIP ports.
>>
>> With the current version of asterisk, which transport is better right 
>> now?
>>
>> I am looking at 6-10 simultaneous calls over a half T1.
>>
>> I am not asking about codecs here, I am asking about SIP vs. IAX if 
>> the provider does either. (we are looking at testing Teliax next)
>>
>> I have seen posts about jitter in IAX, so I am not sure if SIP might 
>> be better to use right now.
>>
>> Also, since IAX uses the same port for all of the calls, the call 
>> separation has to be done higher in the OSI stack. I do not know if 
>> this is better or worse or neither.




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