Configuring the Motorola/Arris SBG6580 Cable Gateway

The ideal network involves your Internet Service Provider (ISP) connecting onsite to a stand-alone modem that connects to a router, preferably a router recommended to you from Nextiva. If you have more devices on your network than ports on your router, you can connect a switch to your router to expand the number of ports.

There are four main areas that you should be concerned with regarding your network. They are:

SIP ALG: Nextiva uses port 5062 to bypass SIP ALG, however, having this disabled is always recommended. SIP ALG inspects and modifies SIP traffic in unexpected ways causing one-way audio, deregistrations, random error messages when dialing and calls going to voicemail for no reason.

Firmware Bugs: There are some known bugs in any version lower than 3.3 that causes RTP drop-offs, which causes audio to cut out and inevitably ending the phone call. 

Bridge Mode Availability: Depending on the ISP, the availability of features will vary.

DHCP DNS Server Configuration: DHCP Option 6 is unable to be changed, which causes intermittent DNS lookup failures that primarily affect Poly devices. Intermittent phone registration failures and call failures are symptoms of this issue. 


To Disable SIP ALG: 


  1. Login to the Motorola/Arris SBG6580 Cable Gateway.
  2. Go to Advanced > Uncheck SIP > click Apply to save the changes.
  3. Setup the new recommended router.

NOTE: Nextiva is unable to set up your new router. The best resource is going to be your ISP, which will move the settings to the new router to make sure all network devices work as desired.

  1. Once the new router is configured, call your ISP to have them bridge the modem. Your ISP may reject your request. However, this is the preferred and most reliable way to configure your network device properly.
  2. If your ISP rejects your request, upgrade firmware to version 3.3 or greater to resolve the previously mentioned RTP issue, then follow the steps below, ensuring no devices are connected directly to the SBG6580 which can cause DNS lookup failures.  
  3. Login to the Motorola/Arris SBG6580 Cable Gateway.
  4. Click Advanced at the top of the page.
  5. Under Passthrough MAC Addresses at the bottom of the page, enter the WAN-Interface MAC address of the new router, then click Add MAC Address.
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