[asterisk-users] Preferred Clock

[Matt Riddell]

On 2/02/2009 11:12 p.m., Chris Knipe wrote:
> Hi,
> 
> We're running on a * 1.4.21 system.  We run about 80 SIP Extensions, mainly
> ATCOM phones (and a few Snoms - 300 and 360), and have an additional 80 IAX2
> extensions to iaxmodem devices for fax2email. We are rapidly growing and 
> will be adding an additional PRI trunk and grow to about 150 SIP & IAX2 
> extensions towards the end of the year.
> 
> We have two Digium Wildcard TDM800P cards (8 x FXO and 8 x FXS) and are busy
> migrating the remaining 8 analogue lines over our ISDN Pri line.  The TDM
> cards are without hardware echo cancellation boards.  The 8 Analogue
> extensions are mainly for traditional paper Fax Machines.
> 
> Our main trunk is a Digium Quad Port PRI Card (PCIe) - with a hardware echo
> cancellation board:
> Span 1: TE4/0/1 "T4XXP (PCI) Card 0 Span 1" (MASTER) HDB3/CCS/CRC4 ClockSource
>         Timing slips: 1
> Only 1 of the 4 spans are being used, the other three has been disabled 
> completely.
> 
> We are getting very strange results on some very intermittant calls.  It is
> not isolated to a single extension or calls to/from a single destination.
> It seems that on random occasions, there are very bad echo (calls via the PRI
> trunk), it sounds like Silence Supression is being used, and there seems to be
> isolated cases that seems to sound more like a sidetone than echo on actual
> conversations / handsets.  All these are only occuring on external calls, 
> internal calls are working flawlessly.
> 
> We've pretty much had this issue intermittantly since day one, had certified
> Digium consultants look at it, independent audits was done, various settings
> has changed and debugged from the Telco side, but those three issues persist,
> and just won't go away. Everyone that looked at the system so far, gave it a 
> pretty clean state and congratulated us on a very well implemented
> installation.
> 
> I am currently using my PRI as my clock source, as indicated above.  Would it
> at all be beneficial to use ztdummy as a clock source instead of the PRI? 
> What would normally be preferred?
> 
> Certain pre-recorded messages, notably those of meetme rooms, sound absolutely
> TERRIBLE on telephones, yet, MOH, and voicemail prompts for example, sounds
> absolutely perfect.  I confirmed and checked, all files being used are the
> same format, and same encoding.  I fail to see why one recording would play
> absolutely flawlessly, whilst another would sound so terrible?
> 
> I would appreciate it if more educated members can possibly engage in a 
> discussion surrounding these issues to hopefully resolve them.  I've worked
> with Asterisk before, but this is my first 'major' implementation in terms
> of a PRI trunk, as well as the number of extensions involved.
> 
> Any configuration files required would be happily provided.  I thank you
> for your time, and effort, and I look forward to hearing from you.

Asterisk version - gcc version - are prompts in GSM?

Don't move away from PRI timing.

What results do you get from zttest?

-- 
Kind Regards,

Matt Riddell
Director
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