[Asterisk-Users] Zaptel T1 Timing Source

[Steve Underwood]

Rich Adamson wrote:

>>Yes, but the problem is, I think from a T1 theoretical perspective,  
>>that because the T1s are from different providers, their timings may  
>>be different. I would assume that I need to be able specify a timing  
>>source per provider. Correct?
>>    
>>
>
>No, all real telco's will sync against a higher level clock, so 
>"they" are already in sync. You only need to pick "one" that you sync 
>from; all others become alternates should the primary source fail.
>  
>
Public telephone exchanges normally contain an atomic (rhubidium) clock. 
The clock in a T1 or E1 from a telco is, therefore, extremely accurate. 
Even if two telcos in different parts of the world don't sync together 
(some do, and some don't) their clocks are still, essentially, in sync. 
This also means that if you derive all your VoIP timing from a public E1 
or T1 clock, and a box the other side of the world does the same, the 
VoIP packets exchanged between them should show no noticable timing 
shifts. :-)

Steve