It is actually possible to clock from an internal source. In a T1, if each end assumes the other end is providing the clock, the circuit is said to be in "free run". Slips and loss of frame alignments can be expected. This is a common mistake made when tying two systems together via a T1 - not designating one end as the timing master. Also, the clock generator in a low-end card is not going to be very accurate, but it'll be better than nothing. So, the analog zaptel cards are providing their own reference clock, which can be expected to be innaccurate, but "good enough" (whatever that means). Lacking a card, some other source of a reference clock is needed. What exactly it is is not that important, as long as it delivers a predictable reference from which a sort of pseudo-clock can be derived. Not perfect by any means, but again, better than nothing. Jim.
-- Jim Van Meggelen [EMAIL PROTECTED] HYPERLINK "http://www.oreillynet.com/pub/au/2177"http://www.oreillynet.com/pub/au/2177 "A child is the ultimate startup, and I have three. This makes me rich." Guy Kawasaki -- _____ From: Frank Perk [mailto:[EMAIL PROTECTED] Sent: March 24, 2006 11:03 AM To: 'Reza - Asterisk Enthusiast'; 'TAUG' Subject: RE: [on-asterisk] Timing Device Hardware (zaptel interfaces) and Software (ztdummy) Reza: Yes, no POTS interfaces (Motorola chipset modems) can be used as a timing source. Any standard timing source can be used. Examples are: * BITS clock with GPS support * Telco timing (ie. T1, DS3) * SNTP Server (don’t just specify it, build a simple clock routing based on the server) * Crystal oscillator * Synthesizer/multiplier It is impossible to clock off a device with no timing source, so just specifying the interface as the clock source without some legit source will create problems. Simplifying the communications world Frank Perk Planet 3 Communications HYPERLINK "http://maps.yahoo.com/py/maps.py?Pyt=Tmap&addr=2810+Sweet+Home+Road&csz=Amh erst%2C+NY+14228&country=us" \n2810 Sweet Home Road Amherst, NY 14228 HYPERLINK "mailto:[EMAIL PROTECTED]" [EMAIL PROTECTED] tel: fax: mobile: Skype ID: 716 929 VoIP (8647) x101 716 929 8648 716 430 6996 frankperk HYPERLINK "https://www.plaxo.com/add_me?u=25770811418&v0=2003852&k0=1750959697"; \nAdd me to your address book... HYPERLINK "http://www.plaxo.com/signature"; \nWant a signature like this? _____ From: Reza - Asterisk Enthusiast [mailto:[EMAIL PROTECTED] Sent: Thursday, March 23, 2006 5:35 PM To: 'TAUG' Subject: Re: [on-asterisk] Timing Device Hardware (zaptel interfaces) and Software (ztdummy) Hello Frank... granted no timing on POTS lines, but what about the FXO devices/cards itself? Everyone without an exception who I personally know running VOIP business - has an x100p/x101p or clone, or a TDM400P or a basic Sangoma A200 - even though not a single RJ-11 PSTN line is going into the cards. So does this mean the x100p/x101p/x100clones are irrelevant as a timing device for MeetMe & MoH functions? If this is irrelevant, how is the timing/synchronizing being done on my boxes where ztdummy was never compiled? Am I missing something critical and obviously silly, or am I opening a new can of worms? :). Cheers! Reza. ----- Original Message ----- From: HYPERLINK "mailto:[EMAIL PROTECTED]"Frank Perk To: HYPERLINK "mailto:[EMAIL PROTECTED]"'Reza - Asterisk Enthusiast' ; HYPERLINK "mailto:[email protected]";'TAUG' Sent: Thursday, March 23, 2006 5:06 PM Subject: RE: [on-asterisk] Timing Device Hardware (zaptel interfaces) and Software (ztdummy) Reza: There is no timing on POTS lines. Only on T1 or higher. -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.3.1/291 - Release Date: 24/03/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.3.1/291 - Release Date: 24/03/2006
