Hi, I'm facing the same issue at a customer site with a SIP line to the provider.
I've already allowed the following ports for the phone:
• UDP/TCP 5060
• UDP/TCP 6000
• TLS 5061 (signalling)
• UDP 8000–60000 (voice / RTP)
I would also like to know where I can enable NAT keep-alive and disable SIP ALG?
I have purchased several devices, but so far I am quite disappointed: without a proper log showing what is being blocked or interrupted, the device is hardly usable.
Best regards
Yves
------------------------------
Yves Poirier
------------------------------
Original Message:
Sent: 01-28-2026 10:59 AM
From: BLimerkens
Subject: VOIP phone issues behind InstantOn SG1004
Hi all!!
I'm having some issues with VOIP phones behind the SG1004 firewall.
Outgoing calls are working fine, but on incoming calls the phone rings but when picking up there's no sound in either direction.
Our telco provider informed us that this most of the time is caused by SIP ALG, but I can't seem to find an option to disable SIP ALG on the Instant On platform.
The SG1004 has a public IP, so directly connected to the internet and on the LAN side it is connected to 1830 24g switch, also Instant On. Phones are connected and POE powered by the switch.
I tried solving the issue by creating some firewall policies but nothing seems to help, disabling Threat Protection has also no influence.
Does anybody experienced the same issue and found a solution??
Thx for your input!
------------------------------
Ben Limerkens
------------------------------