Solved 3CX with Grandstream gxw4248 - Phone not ringing

[moonmotel]

Hi,
I setup a small hotel with 3cx and grandstream gxw4248. Some of the analog handsets are not ringing. Voice communication is established inbound/outbound for both internal/external calls. Just the analog phone does not ring at all when the calls come in. We can pick up the handset and both parties can communicate. Just no ring.

This is only happening on 6 analog phones. We plugged the phones into different ports to see if that is the issue, but the problem follows these particular phones. The phones vary in brand and are Scitec, Aegis and Premier brand phones.

The previous PBX was a Mitel SX-20and this issue was not present when these analog phones were attached to that PBX.

Is this related to cadence, frequency, message waiting or is the phone hardware missing something internally?

 

[JohnS_3CX]

The analog lines have a voltage on them. In order for the phone to ring, the voltage is temporarily increased.

So in very simple terms, either the phones you connected to the GXW are not compatible with the voltage it generates (so they don't detect the ringing state) or the analog cable runs are way too long, and there is a significant enough voltage drop.

You can bring one of the analog phones close to the GXW, connect it with a short cable, and see if it will ring (test 1)

And you can also buy a simple landline phone and connect it to one of the rooms to see if it will ring compared to the older phones (test 2)

 

[moonmotel]

I brought the phone closer and it still doesn't ring. Other analog phones ring. Do you think these analog phones will ring if switched to NEON instead of FSK? Any danger of using NEON?

 

[JohnS_3CX]

Whatever happens on the analog side of the gateway is beyond the 3CX scope because we terminate as SIP on it.

Better ask about this on the Grandstream forums, and it wouldn't hurt to read the GXW documenation first.

 

[leejor]

Ringing current from both the gateway and the SX-20 ( I have one of those) is applied across Tip and Ring, a 2 wire system. So.. as long as the ringing voltage set to output from the gateway is about 90 VAC, the set should ring.

You say this is not happening on 6 analogue sets. Does this mean that other sets, plugged into the same jacks do work correctly? If that is the case, then it is a set issue, and not a gateway issue.

As far as changing the MWI notification, that will depend on what is used in the set. If the set has a neon bulb for message notification, and you want to use this, then the gateway must send 90 volts DC to activate the bulb. Most newer sets use FSK, or Class Message Waiting and have an LED and circuitry to detect a modem burst on the line. Using either one should not affect the phone ringing. If these 6 sets were ringing previously, then I assume that the ringers were not disabled.

Have you tried using them on a standard PSTN line, then calling that number?

 

[moonmotel]

Have you tried using them on a standard PSTN line, then calling that number?

That is the next test we're looking into. I have to find someone with a standard PSTN line!

The phones were ringing before this switch to 3cx.

 

[leejor]

I'm assuming that other sets (other than the 6), plugged into the same jacks are ringing? If some sets do have a neon MWI, it will normally flash at the same time the set is ringing, indicating the presence of ringing current.

As I said, the sets should be using a bridged ringer if previously used on an SX-20. This means that the ringer is bridged across Tip ans Ring, the two conductors used for talk current. Some sets, particularly, in places like the UK, connect the ringer across the Ring lead and one other wire , not tip. They use a "special" master connector block that then brings the ring current from the Tip lead to that third wire. This means that some re-wiring needs to be done to use them on a two wire circuit. That shouldn't be that case, but....maybe?

 

[moonmotel]

It could be that whatever fried a board in the mitel sx-20 during a recent storm (power surge) likely affected a few handsets also. Its much cheaper to just replace them at this point then to mess with all the particulars of the ringer.

I appreciate everyone's help and guidance. If anyone wants a mitel sx-20 along with a console for parts, etc. PLease DM me. If this is against forum policy, I apologize in advance.

This thread can be closed.

 

[leejor]

It certainly is possible. Were the setts that are now not working , using the line circuit board that fired? Given that most modern sets use electronic ringers, connected across the line at all times, it is certainly not inconceivable that a high voltage lightening hit blew a ringer component out. I hope that if you're area is subject to this sort of activity, that you have now installed some sort of surge suppesion system, or even a UPS, ahead of your server and gateway.