[VoiceOps] Mitel 3300 Issues

Jay Hennigan jay at west.net
Tue Mar 15 13:27:54 EDT 2022

On 3/14/22 13:50, Mike Hammett wrote:
> A customer of mine has a Mitel 3300 PBX. We deliver to them analog lines.
> Everything worked fine for months, if not years. Then one day they say 
> they can't receive inbound calls. They can still place outbound calls.
> They're on a Grandstream HT818 ATA. I move some lines to the Zhone ONT 
> that's on-site. No improvement.
> I plug in a normal analog handset from Walmart or Menards. They all ring 
> and answer just fine.

Mitel and some other PBXs have the ring voltage detector between the 
ring lead and ground as opposed to across tip and ring. This is true if 
optioned for loop or ground start. If your ATA or Zhone doesn't have a 
ground reference then the ability of the PBX to detect ringing voltage 
will be problematic. Sometimes it works, sometimes not. Sometimes 
reversing tip and ring will fix it. If the Zhone or Grandstream have a 
ground terminal on the chassis, try connecting it to the same ground as 
the PBX uses.

The analog lines of Adtran TA9XX will work fine. Adtran nailed POTS 
emulation perfectly in these boxes. Tie the chassis ground screw on the 
Adtran to the same ground as used by the PBX.

Better, put the TA9XX in and feed the PBX via PRI. Essentially zero 
post-dial delay. In addition, CNAM, CLID, etc. will now just work.

Jay Hennigan - jay at west.net
Network Engineering - CCIE #7880
503 897-8550 - WB6RDV

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