[Asterisk-Users] Freak incidents, who's to blame?

[Eric Wieling aka ManxPower]

Ryan Courtnage wrote:
> 
> On 3-May-05, at 10:34 AM, Eric Wieling aka ManxPower wrote:
> 
>> Ryan Courtnage wrote:
>>
>>> Hello all,
>>> Everyone has probably experienced this at some point in the past:
>>> You pick up your analog phone.  Rather than hearing dialtone, you  
>>> are  connected with someone who has just called you.  Neither you  
>>> nor them  heard a ring.
>>> Maybe it's just me, but it seems these "freak incidents" would  
>>> occur  more frequently years ago, than now.
>>> I've now experienced this a couple of times with an * system  
>>> (TDM400p  - quad FXO):
>>> A SIP exten dials digits which are answered by a Zap trunk.  As  
>>> soon  as Zap answers, the SIP extension is connected with an  inbound 
>>> (PSTN)  caller (who was expecting to hear an IVR).
>>> My questions are:  Who's to blame (telco, tdm card, * config,   
>>> gremlins)?  Is this avoidable?
>>>
>>
>> It's called "glare".
> 
> 
> Thank you, I'm now walking down the right path.
> 
>  From what I've read, glare is common in 2-way loopstart (kewlstart)  
> circuits, and is impossible(?) to eliminate completely.  But now I'm  
> wondering what Nortel would tell a customer who experiences glare on  
> their new Meridian system... they must do something to prevent glare  
> from happening.  Any ideas?

They would tell them to use groundstart or E&M wink ports, and then tell 
them that the loopstart cards they bought won't work with the other 
signaling methods and have to be replaced.

--Eric