Networking Guidelines
Guaranteeing the best audio quality with Nextiva Voice service involves maintaining a stable Internet connection and configuring the local network with the correct settings. See the guidelines below to ensure the local network is operating at peak efficiency.
- Verify the local network quality: Bandwidth, Packet Loss, and Jitter
- Add Firewall Access Rules
- Remove Double NAT
- Disable SIP ALG
Common Network Configuration
Below are two common ways Nextiva recommends having your network configured. One is utilizing a gateway, often provided by your Internet Service Provider (ISP), and another is utilizing a modem and router.
| ISPs that rely on wireless technology, such as 5G or satellite internet, are considered unsupported due to the increased likelihood of packet loss. This usually results in choppy audio during phone calls and cannot be remedied by Nextiva support. Nextiva recommends a wired connection, such as cable internet or fiber, for the best experience. |
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| Network Components | Description |
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Your ISP provides you with a connection to the Internet. Wireless or satellite ISP services are not recommended as they have been shown not to have sufficient quality to support real-time traffic. See the section below for Nextiva's bandwidth requirements per device. | |
| A modem is required with cable or DSL Internet connections. It converts the DSL or Cable signal into a signal your computer and phones can use. | |
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A router is a bridge between your local network and the Internet. Ensure that you only have one router on your network; otherwise, you run the risk of a double NAT. Quality of Service (QoS) settings are recommended to prioritize voice traffic to optimize call quality, though not all routers support QoS functionality. | |
| A gateway is a modem and router combined into a single unit. Most Internet Service Providers (ISPs) will provide one with service. Many of these ISP-provided gateways have very simplified user interfaces that prevent advanced configuration. As such, Nextiva will usually recommend using a standalone modem and router instead of the gateway. If your ISP requires their specific gateway for internet service, you may be able to have them bridge the gateway to a standalone router to avoid double NAT. | |
| Switches add additional wired connection points for your network. Some switches can provide Power over Ethernet (PoE) allowing you to provide power to your phones without using an AC power adapter for your phone. | |
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Phones purchased from Nextiva will auto-provision themselves once they are assigned to your account. Most deskphones today have an extra gigabit switch port on the back to connect to a computer. If the phone has two ports on the back, please ensure that the device is plugged in using the LAN port. | |
| If each workstation in your business has only one Internet connection, the PC can be connected to the PC port on the back of the phone. | |
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Nextiva recommends using Cat5e or Cat6 Ethernet cables for your network. For optimum quality, all phones should be hardwired. |
Verifying the local network quality: bandwidth, packet loss, and jitter
The underlying Internet connection from a local ISP is the most critical factor in delivering high-quality audio. Low bandwidth, packet loss, or jitter causes choppy audio, voice delays, echoing, and dropped calls for Nextiva customers.
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Adding Firewall Access Rules
Firewall Access Rules control the flow of inbound and outbound Internet traffic from the local network to the public Internet. Both routers and firewalls use access rules to control traffic and verify the source and destination addresses are permitted to send and receive traffic on the local network.
Click here for a range of IP addresses to allow through your firewall.
Many router and firewall manufacturers have different interfaces. Nextiva suggests that a network administrator familiar with the local networking equipment enter Nextiva’s Firewall Access Rules.
After configuring the firewall, move Nextiva’s access rules to ensure that any access rules blocking Internet traffic are prioritized below Nextiva’s access rules.
Removing Double NAT
Double NAT (Network Address Translation) causes intermittent issues that include but are not limited to:
- One-way audio
- Phone Deregistration
- Unsuccessful transfers
- Error messages when dialing a phone number
- Call Groups not ringing properly
- Dropped Calls
Routers and Gateways are both networking devices that perform NAT, which helps route incoming Internet traffic to the correct device on the local network. Nextiva recommends that a Network Administrator ensure the WAN IP of the local network is an IP address that falls outside the private address ranges in the ranges below:
- 10.0.0.0 - 10.255.255.255
- 172.16.0.0 - 172.31.255.255
- 192.168.0.0 - 192.168.255.255
Disabling SIP ALG
SIP Application-level Gateway (SIP ALG) or SIP Transformations, depending on router type, is a feature that routers use to help external sources contact devices that are on their own local network. At Nextiva, we do something called "Far-end NAT", which means we can contact the local IP addresses of phones while still addressing the proper WAN IP address that a network is on. SIP ALG causes issues with our service in that we expect a local IP address to be sent to us as a contact, but SIP ALG changes the contact information that is coming through on port 5060 and labels it with their WAN IP address. This causes issues with the information sent to a phone, most commonly causing one-way audio, missed calls, and calls disconnecting mid-call.
Manufacturers often enable SIP ALG by default, and since this setting only affects VoIP services, SIP ALG often goes unnoticed.
To mitigate this problem, Nextiva sends VoIP traffic over ports 5062 to 5090. However, even with this safeguard, SIP ALG can cause one-way audio, deregistrations, or dropped calls. Nextiva recommends the network administrator disable SIP ALG on the router or firewall.