Using Third Party VOIP Provider With Telstra HFC NBN & Gen 2 "Smart" Modem

[AliveWriter]

I currently have HFC NBN with Telstra and a Gen 2 Smart Modem. I also have a home phone number with Telstra that works fine. However, I also have a Grandstream work desktop phone with a different VOIP provider that's now connected to my home internet so I can use the work phone system from home. It's all setup, however I cannot make outgoing calls. I can receive them fine, but not make them. I have spent hours on support calls with the VOIP provider and Grandstream. They cannot figure out why outgoing calls wont work. The other VOIP provider also stated none of the calls I'm dialling are reaching or registering in their system and they said the SIP ALG settings in my modem might need to be disabled. I understand Telstra don't allow this, so how can I get around it?? I am going to be working from home for the foreseeable future and I need this device to work properly.

[cf4]

SIP ALG usually causes problems with incoming calls. There are no SIP ALG settings in the Telstra modem. I have a third party VOIP service and have no problem's making or receiving calls on my Telstra NBN Internet connection. One thing you could try is to put the Grandstream work desktop phone in the DMZ of the modem.

[AliveWriter]

Hey, thank you for the response. I added the phone to the DMZ of the modem, but it hasn't worked. I still can't make outgoing calls. So I'm at a loss as to why this isn't working. If both the VOIP and handset providers can't figure it out, I don't know what I'll do. I can make and receive calls using a soft phone app from Grandstream on my iPhone, but that's only a temp fix for now. I'll need the desk phone working soon.

[cf4]

Does the iPhone soft phone work when iPhone is connect to modem's WiFi. If it does then there is an incorrect setting in the Grandstream phone.

[AliveWriter]

It's funny you asked that because I just tried it on wifi after I posted that message, and the soft phone app can make outgoing calls when the iPhone is connected to wifi. So you're right, there must be an issue with the settings of the desktop phone. I've had the VOIP provider and Grandstream check and they both confirmed it was configured correctly, so... I honestly have no idea.

[AliveWriter · Accepted solution]

I just got the desktop phone working. I did a factory reset and put the VOIP account details back into the device via the web browser and it seems to be working now. Not sure what went wrong, or what the other two tech support people were looking at. Anyway... it's doing what I need it to now. :-)