Cannot hear ringing tone on the calling phone

[ZakLuthfy]

Hi guys,

i'm in need of assistance, I've a strange situation.. i've install 3cx V16 set up SIP Trunk as a "Generic SIP TRUNK provider", can properly receive incoming and make outgoing calls via 3cx. But the problem is I cannot hear anything while ringing (incoming calls) its dead silence

when I call the DID numbers of the SIP trunk I don't hear any tones (ringing tone) on the phone. the internal reception phone that is set to ring upon incoming calls, ringings but on the phone (my Mobile phone) that is calling I don't hear anything. however if the call is picked up the audio works just fine, i can hear and talk both the way as a normal call.. just when calling there is no ringing tone which is difficult, as the caller does not know if its ringing or busy etc.... i know this isnt anything related to SIP provider because, if i setup the account on a desktop softphone i can hear the ring tone etc.

Firewall checked on 3cx, there are no errors, all the ports required are opened, below are rules set on the router.

• 3CX Version, Professional Annual V16.0.676
• Server OS, Windows 10
• Is the 3CX Server Hosted and where: locally Hosted
• IP Phone Make/Model/Firmware: GrandStream GXP1615 15phones FW:1.0.4.132
• Provisioning Method: Local
• Trunk Provider: YES
• Has the Firewall Checker passed: YES
• Are custom Phone Templates being used: YES

 1    chain=dstnat action=dst-nat to-addresses=x.x.x.x to-ports=9000-9500 protocol=udp in-interface=ether1 dst-port=9000-9398 log-prefix=""
2    chain=dstnat action=dst-nat to-addresses=x.x.x.x to-ports=10600-10998 protocol=udp in-interface=ether1 dst-port=10600-10998 log-prefix=""
3    chain=dstnat action=dst-nat to-addresses=x.x.x.x to-ports=5060 protocol=udp in-interface=ether1 dst-port=5060 log-prefix=""
4    chain=dstnat action=dst-nat to-addresses=x.x.x.x to-ports=5090 protocol=udp in-interface=ether1 dst-port=5090 log-prefix=""
5    chain=dstnat action=dst-nat to-addresses=x.x.x.x to-ports=5060 protocol=tcp in-interface=ether1 dst-port=5060 log-prefix=""
6    chain=dstnat action=dst-nat to-addresses=x.x.x.x to-ports=5061 protocol=tcp in-interface=ether1 dst-port=5061 log-prefix=""
7    chain=dstnat action=dst-nat to-addresses=x.x.x.x to-ports=5090 protocol=tcp in-interface=ether1 dst-port=5090 log-prefix=""
8    chain=dstnat action=dst-nat to-addresses=x.x.x.x to-ports=5001 protocol=tcp in-interface=ether1 dst-port=5001 log-prefix=""

please help. and thank you for your time.

 

[JohnS_3CX]

Hello Zak and welcome to the community forum!

You have to tell us more about how the call is routed to the phone from the trunk (in detail), it could be any number of things. A couple of examples below

One possibility:
If you are not hearing the ringback tone (or progress tone), then it might actually be related to your trunk provider. They have to play that tone when the PBX replies "180 Ringing" to the "Invite" message

Since you are probably not using a supported trunk provider, we cannot know why this happens unless you run a capture or speak with your provider about it. I suspect they will have to change something on their side.

Another possibility:
You are sending the call to a queue, and you have a silent music-on-hold. The call is answered and put in the queue and the deskphone is ringing. But the caller hears silence because you are sending silence to them for whatever reason

 

[ZakLuthfy]

Hello Zak and welcome to the community forum!

You have to tell us more about how the call is routed to the phone from the trunk (in detail), it could be any number of things. A couple of examples below

One possibility:
If you are not hearing the ringback tone (or progress tone), then it might actually be related to your trunk provider. They have to play that tone when the PBX replies "180 Ringing" to the "Invite" message

Since you are probably not using a supported trunk provider, we cannot know why this happens unless you run a capture or speak with your provider about it. I suspect they will have to change something on their side.

Another possibility:
You are sending the call to a queue, and you have a silent music-on-hold. The call is answered and put in the queue and the deskphone is ringing. But the caller hears silence because you are sending silence to them for whatever reason

Thank You, John, for your reply. I’m new to 3cx forum, I’ll try my best to explain it here.



Sip is created with IP based authentication.

I’ve setup a “Ring Group” added two extensions to ring simultaneously > ring strategy is set to “Ring All”. If the call is not answer is set to “end call”

180 Ringing > strangely, if I setup my credentials for SIP on a softphone, I can hear the ringback (progress tone) … when I set the account in 3cx then I don’t.

No inbound rules have been created. Only Outbound Rules are in place.

Is ringing group is a queue? I thought im sending the call directly to the receptionist phones, under call queues, there is nothing setup.


Please refer to my screenshots,

 

[JohnS_3CX]

The ring group appears to be fine, there is no music on hold for ring groups so we can discard that scenario.

Allow me to get a bit more technical, and hopefully explain put things into perspective. The below is specifically for incoming calls where we receive the call on the PBX:

1. someone calls your DID from their mobile line
2. their mobile provider contacts your trunk provider and says you have a call from this mobile number
3. your provider "Invites" the PBX and says we have an incoming call from this mobile number
4. Your pbx says "180 Ringing" and then makes the GrandStreams ring

As you see, there are at least 2 people in the middle before that mobile reaches your PBX

• The mobile carrier
• The Trunk provider

If we reverse the direction now when the PBX replies "180 Ringing" to the trunk provider, it is their job to reply to the mobile carrier the same.

Here is where things might go wrong: If they don't do 180 as above, and instead they reply 183 then they also have to send the ringback sound to your mobile carrier. if they don't then the mobile will hear silence. I think you should discuss it with them to see if they are causing this issue or if it is the mobile carrier that refuses to play the ringback.

You can run a capture under your management console to see what your PBX replies to the invite from the provider during an incoming call, just to verify that 3CX replies "180 Ringing" and eliminate it from the loop. Then move up to the trunk provider, and if needed to the mobile carrier

 

[ZakLuthfy]

The ring group appears to be fine, there is no music on hold for ring groups so we can discard that scenario.

Allow me to get a bit more technical, and hopefully explain put things into perspective. The below is specifically for incoming calls where we receive the call on the PBX:

1. someone calls your DID from their mobile line
2. their mobile provider contacts your trunk provider and says you have a call from this mobile number
3. your provider "Invites" the PBX and says we have an incoming call from this mobile number
4. Your pbx says "180 Ringing" and then makes the GrandStreams ring

As you see, there are at least 2 people in the middle before that mobile reaches your PBX

• The mobile carrier
• The Trunk provider

If we reverse the direction now when the PBX replies "180 Ringing" to the trunk provider, it is their job to reply to the mobile carrier the same.

Here is where things might go wrong: If they don't do 180 as above, and instead they reply 183 then they also have to send the ringback sound to your mobile carrier. if they don't then the mobile will hear silence. I think you should discuss it with them to see if they are causing this issue or if it is the mobile carrier that refuses to play the ringback.

You can run a capture under your management console to see what your PBX replies to the invite from the provider during an incoming call, just to verify that 3CX replies "180 Ringing" and eliminate it from the loop. Then move up to the trunk provider, and if needed to the mobile carrier

i've done a capture, attaching you screen print... what do you suggest further?
i think 180 Ringing is send from 172.18.5.110 (3cx system) to 172.31.241.10 (Sip Provider) i hung up the phone on line 6 to make the logs shorter.

 

[JohnS_3CX]

Ok since you have the reply "180 ringing" then your PBX is doing its job correctly.

Next step is to inform your provider that this happens, and use the capture as proof that the PBX says 180 (not 183+SDP). They then need to see what they send the call to the caller through their own logs/captures on their end.

If your provider is also sending 180 to them, then there is not much else you or your provider can do, it then depends on the rest of the route.

I speculate that either the mobile carrier is doing something wrong, or the route from your provider to the mobile carrier has a small mistake somewhere that causes this. They must also investigate their end of course, so we can learn the facts, and perhaps make changes if needed. Lets see what they say.