Chris Deren Mon, 02/16/2009 - 15:07
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PLAR - Specifies a private line automatic ringdown (PLAR) connection. PLAR is an autodialing mechanism that permanently associates a voice interface with a far-end voice interface, allowing call completion to a specific telephone number or PBX without dialing. When the calling telephone goes off-hook, a predefined network dial peer is automatically matched, which sets up a call to the destination telephone or PBX.

PLAR OPX - Specifies a PLAR off-premises extension (OPX) connection. Using this option, the local voice port provides a local response before the remote voice port receives an answer. On Foreign Exchange Office (FXO) interfaces, the voice port does not answer until the remote side has answered.



lagos Mon, 02/16/2009 - 17:08
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When you use plar, the port goes off-hook on the 1st ring and then the call is placed. From a call state standpoint, the call is connected even if it's never answered.

Using OPX, the voice port doesn't go off-hook unless the call is answerd. This can work with CUCM for example. One thing I've found is that sometimes we need "no battery reversal" for the feature to work correctly with PSTN pots service.


titomontos Tue, 02/17/2009 - 05:37
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Can we say that PLAR is used over WAN and PLAR OPX using over PSTN?

Nicholas Matthews Tue, 02/17/2009 - 18:48
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Hi Tito,

Plar OPX should 'cut over' the audio stream when we either get progress with in-band information, which is ringback, or a connect.

The difference between the two was for older IVRs that would not operate correctly sometimes if it was simply plar'd to, and we needed to wait until we actually had audio to cut through.

Generally if the extension isn't directly connected to the box, you can use opx. I haven't personally seen much of a difference between the two, for what it's worth.



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