Level 1: Cadet

Router blocking Zoom Phone

Hi There,


I am currently working from home and my company is about to switch to Zoom Phone.

Doing some tests we discovered that my Netgear Telstra Gateway Max C6300bd-1tlaus router is blocking zoom phone somehow.


Tech support at zoom pointed me to this page but unfortunately they are not authorized to make any changes to my device.


Could you please send me instructions on how to update my router setting to allow traffic from Zoom Phone?

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Level 21: Augmented
Level 21: Augmented

Re: Router blocking Zoom Phone

Hi - I have no experience with Zoom Phone but from watching YouTube clips, it looks impressive.


When you say that you are pre-testing Zoom Phone as part of your company switching to using the application for their company wide Unified Communications platform for Voice, Video and Mobile communications, are you actually using the Zoom Phone App that has been pre-activated for you by your Systems Admin staff. They would have assigned you an allocated extension number or are you attempting to test it through just a web page? 


A few questions


1. Is the Zoom Phone App loaded on your mobile phone, laptop or desktop PC and registered on line to your company's account and it shows you your extension number - does it work on the mobile phone's 4G LTE which would bypass the modem ? 

2. If you only have the Zoom App downloaded - does it work for video conferencing only?

3. Are you attempting to connect Poly or Yealink  VoIP SIP phone to the modem so that you can use it for traditionally desktop telephony? That would require a hosted VoIP subscription with Zoom.  


I take it you are on a legacy BigPond HFC service with this modem. The above Zoom URL refers to having specific Outbound ports open for Zoom and then additional outbound ports open for Zoom Phone. This may be applicable to large businesses that have strict Firewall rules for outgoing connections made by their staff. I don't think these rules apply to residential modems as all outgoing ports in Telstra modems are usually Open.


All incoming ports are Firewalled to prevent unauthorised remote access unless they are as a result of a user initiated outgoing request. Firewall settings also usually exist to lower the protection level as required, however I would not recommend that.  With the Firewall setting on default High, special exemptions can be programmed for certain Incoming Ports only to open in the Games and Services section Port Forwarding ( once set they are open 24/7) or Port Triggering ( only applicable after an App requests connection).


To my knowledge, the only other place that can trap an outgoing connection request is Telstra Broadband Protect ( the no fee subscription service include by Telstra) - usually this can be avoided by changing the Primary DNS and Secondary DNS e.g. to Google's and, however given that this is an old combination HFC modem/router, I don't know if the fields can be edited. My Netgear test modem is connected as a secondary router via its WAN port to another modem, so its DNS entries are empty and I can't edit them - usually, in this application I would have expected the DNS entries to show the IP address of the primary modem but they are empty on mine. The DNS entries in the Netgear may only show up when the modem itself is directly connected to the HFC service.  


Suggest you check with your IT Department to see if other staff have it working for them and what equipment and service works. It maybe that your home network and service has to be upgraded, however it still should work on your mobile phone when its is on 4G LTE.  

Level 1: Cadet

Re: Router blocking Zoom Phone

Thank you for the detailed reply @Mkrtich


Zoom have granted us temporary trial licenses to test the system prior to committing. I am logged into the zoom iphone app with the same access as a licensed user and i have been assigned an extension number.


The app works perfectly fine when I am connected to 4g, or when i am connected to the wifi network at our HQ office.

Video conferencing works fine, it seems its only audio that is affected, and it is only phone calls through the Zoom phone app (i.e. Extension to extension calls via the app experience the issue, however when a colleague on a different network uses zoom to phone my mobile number (as if they were calling a customer) the audio is fine.


Interestingly exactly the same thing happens on my macbook pro for extension to extension calls via the zoom app.


To be more specific about the issue I am experiencing - My colleague can hear me talking but i cannot hear them. From my endless amounts of googling for a solution i figured out this is referred to as one way audio.


I have a couple of colleagues also testing the app and they have not had any issues, neither are using a telstra internet.


My connection is a Telstra cable connection. I have setup port triggering with some instructions from Zoom, however that did not solve the issue and i do not seem to have permission to update DNS.


I have liaised with Telstra directly over live chat and they have performed various tests resulting in the conclusion that there is nothing wrong with my internet connection. My next step will be to factory reset the modem as suggested by Telstra.

Level 21: Augmented
Level 21: Augmented

Re: Router blocking Zoom Phone

Thanks for clarifying the situation with your feedback. So outgoing calls are OK which means Telstra Broadband Protect is not interfering. Incoming audio on calls is not being let through or lost in transmission. The rules that Zoom suggested, was it to do with incoming ports 5060 and 5061 which are usually to do with VoIP TCP and UDP?


Unlike the Optus version of the Netgear modem, the Telstra version of the C6300bd has no Voice Ports, so unsure if its special firmware influences your situation. Sometimes a modem reset clears up a one way audio problem - I had this once with my Gen 2 Arcadyan modem. Others times , it is suggested to ensure the SIP ALG setting in Services is Disabled - in my Netgear test modem which was factory defaulted before use, SIP ALG was the only service that was Disabled - all others are Enabled on start up.


On NBN, the Telstra Gen 2 modems have no ability to Disable SIP ALG. 



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