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A question on number of phones supported

Started by cde552, June 24, 2014, 01:47:22 PM

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cde552

We have been looking into purchasing an Obi110. What we need to be able to do is support 6 phones or so over our house wiring (over 100 feet of cable), on the FXS port. Can the Obi support this many phones? I know it should be possible as rental units from the cable co. have been able to do this for us.

The other question is can we configure the Obi to route all calls from the phone port, FXS port, to the PTSN port, the FXO port. What about routing a small block of numbers dialed on the FXS port to an Asterisk server, and sending all other calls out on the FXO? Could it also be possible in such routing to automatically prepend an area code to 7 digit numbers dialed on the phone port, before they are sent out on the PSTN port.

Later on, if I decided to, could both the FXO and FXS ports be configured to connect independantly to Asterisk servers, so that all incoming calls on the FXO would go to Asterisk via SIP, and all outgoing calls on FXS should go to Asterisk.

drgeoff

Number of phones depends greatly on the phones.  It is really only a ringing issue.  Traditional phones with real bells require a substantial amount of electrical energy to make them ring.  Phones with electronic ringers tend to require less.  The OBis are specced at REN=5.  You need to total up the RENs of the 6 phones; a total of 5 or less should be OK.

Yes OBi dial plans are able to accomplish such routeings.

Yes, an OBi110 can be configured to work in harmony with Asterisk.

cde552

Thank you, that is good to hear. 5 REN should be enough. One reason I ask this is that ive had a magicjack where if you have more than 3 phones off the hook at any time, the recievers on some phones start to go dead, usually the phone that is physically located closest to the magicjack. Magicjack though is a low grade device that has cheap electronics, the thing does not have enough power it seems to support more than 2 phones, so what I need is something that is better built that can support the house phones.

I am looking for a device that can really put out a lot of power on the line to support the phones, and is also configurable to the hilt so that I can have something which is flexible and I can repurpose if I need to.

drgeoff

If you want multiple phones off-hook simultaneously, ie all of them talking/listening, that is different from REN.  I don't think OBi publish a spec for that aspect.  I would expect (= an optimistic guess!) that two would be OK.  I think you will not know until you try.  Unlike the ringing, the type/make/model of phone will likely have much less impact.

sailing

In Physical Interfaces > Port Settings the setting OffHookCurrentMax limits the current to the phones when they are off hook. If you find problems with phones not working as you use more of them simultaneously, you could increase this number. (This setting limits the max current.)

Another issue could be the wiring in your house. With enough phones off hook, there may be enough voltage drop through the wiring that would cause phones to not work. In this case, the above setting changes will not help.