Recommended Internet and Network Settings

Recommended Internet and Network Settings

Overview


For optimal performance and reliability with Primevox services, certain internet and network configurations must be applied to your firewall, router, and other network equipment. These settings ensure stable SIP registration, consistent call quality, and reduced risk of call drops or audio issues.

This guide provides recommended settings, preferred equipment lists, and modem-specific guidance for several major internet service providers (ISPs).


General Required Settings


Regardless of your ISP, the following settings should be applied wherever possible:
  • Use TCP instead of UDP for SIP transport.
  • Disable SIP ALG (Application Layer Gateway).
  • Disable IPv6.
  • Disable built-in firewall features on ISP-provided modem/router equipment if you are using your own firewall.


Provider-Specific Recommendations



AT&T / DSL / U-Verse
  • Required Settings:
    • Use TCP instead of UDP.
    • Disable SIP ALG.
    • Disable IPv6.


Frontier / Verizon Fios
  • Required Settings:
    • Disable SIP ALG.
    • Use TCP instead of UDP.
    • If using your own firewall, disable the built-in firewall on the ISP modem/router to avoid double NAT.
  • Note: These fiber-based services are generally reliable, but default configurations may interfere with VoIP.


Xfinity / Comcast
  1. Good / Preferred Modems
    1. Netgear CM500
    2. Netgear CM600
    3. Netgear CM1000
    4. Arris SURFBoard SB8200
  1. Bad Modems
    1. Netgear CM700
    2. Motorola
    3. Arris SURFBoard models except SB8200
    4. Cisco (DPC Series)
    5. SMC
    6. TP-Link
    7. Zoom
  1. Required Settings
    1. Disable IPv6.
    2. Disable entire firewall.
    3. Disable SIP ALG.
  1. If You Have a Bad Modem
    1. Comcast allows customers to purchase their own modem. Recommended: Netgear CM500 or better. Call Comcast to register the new modem before installation.
  2. Why Bad Modems Cause Issues
    1. Older or low-performance modems can’t handle the processing demands of multiple simultaneous phone calls, resulting in jitter, packet loss, and degraded audio quality—even if general internet browsing appears fine.


Spectrum / Time Warner Cable
  1. Good / Preferred Modems
    1. Arris DG1670
    2. Netgear CM500
    3. Netgear CM600
    4. Netgear CM1000
    5. Arris SURFBoard SB8200
    6. New Spectrum-branded modems
  1. Bad Modems
    1. Netgear CM700
    2. Arris TG862G
    3. All SURFBoard modems except SB8200
    4. Motorola
    5. Technicolor
    6. Ubee
  1. Required Settings
    1. Disable IPv6.
    2. Disable entire firewall.
    3. Disable SIP ALG.
  1. If You Have a Bad Modem
    1. Call Spectrum and request an Arris DG1670. If asked why, explain that the existing modem is causing VoIP packet loss and that the Arris model resolves the issue.
  2. Why Bad Modems Cause Issues
    1. As with Comcast, outdated or underpowered modems can’t process high-quality voice traffic reliably, leading to jitter, packet loss, and poor call quality.
  3. Identifying Spectrum’s Two Boxes
    1. Spectrum may install two devices:
      1. A small Motorola modem (used for Spectrum’s public hotspot) — can be unplugged if desired.
      2. A larger modem that connects to your network — this is the one that matters for VoIP.


InfoIf you are unsure how to apply these settings or select compatible equipment, contact Primevox Support at support@primevox.net or call 972-600-1150, option 1.

    • Related Articles

    • Approved Routers / QoS Settings

      Overview The following Quality of Service values are used with all phones registered to the Primevox infrastructure. All router models by these manufacturers are supported by our VoIP services. SIP Signaling: 26 / AF31 / 0x68 (UDP or TCP) RTP Audio: ...

    • Extension Settings

      Introduction What is an Extension? An extension is a unique number assigned to a user, phone, or device within your organization’s phone system. It serves as a direct internal line, allowing colleagues to reach each other quickly without dialing full ...

    • Call Flow Settings

      What Are Call Flow Settings? Call Flow Settings allow users customize how calls are routed based on the time, preset rules, or manual override toggles. This includes things like setting business hours, creating special schedules for holidays, and ...

    • DNS Settings for Legacy (Green) PBX Portal

      Setting Up a Custom PBX Domain (CNAME) You can create a custom login URL for your customers, such as "pbx.yourdomain.com", to provide branded access to the phone system. Follow the steps below to configure and activate your custom PBX domain. Step 1 ...

    • DNS Settings for Branded Emails in Legacy (Green) Portal

      Overview In order to authorize the Primevox Mail Server to send emails on your behalf, you must have an SPF Record that allows our mail server's IP address. Also, a DKIM Record is required for our servers to encrypt emails to your customers. We DO ...