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koolandrew

Best Practices for Multicast Paging using Snom PA1

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There isnt alot of information regarding this topic, so hopefully the response will be useful for others as well.

Three options

No pbx involvement with paging

1. I have gathered that you put the mulitcast ip address from the PA1 and copy it to the mulitcast settings on whatever brand of phone you choose ie (224.1.1.2:4000) so they will ring at the same time as when the shortcut key on the phone is selected with this value.

Pbx involvement

2. Call the paging extension (unicast) and put the SNOM PA1 extension number in as one of the extensions to be dialled. It in turn broadcasts through the multicast ip to the other phones that are selected.

3. Call the extension number of the PA1 directly from any phone to start a page and the other phones will broadcast as above.

Thanks

 

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One important question is if this happens within the same LAN. If the answer is yes, then multicast can be a good option (unless call recordings is required). In that case, you can just provision the PA1 be part of the paging group and have the phones permission to page that group. Then the PBX will take care about provision everything to work peer to peer.

If your desktop phone does not support sending multicast RTP or you want to use the feature e.g. from a PSTN or Microsoft Teams account, then the PBX can still generate multicast. This would require that the PBX and the PA1 are in the same LAN. 

If neither a phone that can generate the multicast RTP nor the PBX is in the LAN, then we are talking about sending the RTP over unicast SIP. This is easy if there is just one PA1. If there are many PA1, it becomes more and more difficult to have them all play back the page as the load on the system goes up, which is especially a burden if you are on hosted PBX with limited bandwidth into the LAN. In that case there is an option in the PA1 to relay the unicast RTP into multicast RTP. However the PBX does not support provisioning that kind if scenario and this would have to be set up manually.

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Thanks for the quick reply.

All the phones support multicast paging, there is only one PA1 and they are all on the same lan.

Are you suggesting, creating a Unicast paging with the PA1 extension only in the group, and using the PA1 to multicast to all the phones that have the multicast ip setup.

In this case, the pbx would effectively only unicast to the Snom PA1 and it in turn would multicast to the phones that have been setup?

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If everything is in the LAN, all you have to do is to put the multicast paging group on the button of a phone and provision the PA1 and the phone. Then when you press the button it will be sent from the phone to the multicast group and make the PA1 play it back. The PBX will be unaware about it—no CDR and also no call recording.

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Ok, this still a little vague...please remember as your status says "Advanced Member", i dont have all your knowledge.

When you say "Multicast Paging Group" what do you exactly mean.  i am just manually provisioning to get this to work. IThe choices, on a Grandstream, for example are, to add the multicast ip (224.1.1.2:4000) in the multicast paging section and give it a label of page. I go to the vpk section to add a button. I add the description of Page, and value of 224.1.1.2:4000, and select Multicast Paging. I could also select Multicast Listen Address, but i dont believe that is what you are suggesting.

It actually worked, with no pbx cdrs as you said, the only difference that the PA1 and the other phones play the message.

THE BIGGEST ISSUE REMAINING IS THAT THE MESSAGE IS ALSO PLAYED FROM THE PHONE THAT YOU ARE CALLING FROM, HOW TO PREVENT THAT NUISANCE, AS THE PLAYBACK IS AWFUL

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In the PBX, paging accounts can be in unicast or multicast mode. The latter one would be a "Multicast Paging Group". Entering 224.1.1.2:4000 there is a good choice. You can provision the button also from the PBX without having to touch the phone—the PBX would then set up the VPK button automatically. Just select the paging account for the button and hit the save button.

As for the echo, that is a good point. There must be a setting that tells the phone that it should not play back its own RTP stream. IMHO it would be reasonable that this is "on" by default. Unfortunately Grandstreams many models all have different provisioning profiles which make it hard to take care about each and every model. Other vendors keep the name of the settings across large amount of devices.

 

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