Voice over IP (VoIP) is a critical communication tool for businesses and individuals alike. To ensure the best VoIP experience over a wireless network, it's essential to configure your WiFi network properly. This guide provides comprehensive guidelines for configuring VoIP on Zyxel devices, ensuring VoIP integrity, and enhancing overall performance.
Section 1: VoIP Considerations
1.1 Understanding VoIP Characteristics:
- VoIP requires real-time transmission/conversation.
- Voice packets lack integrity checks.
- Latency significantly impacts conversation quality.
1.2 Goals:
- Provide guidelines for optimizing VoIP performance.
- Improve VoIP integrity.
- Identify complementary features.
- Highlight features to avoid.
- Extend guide to Nebula Switch configuration.
Section 2: WiFi Setup for VoIP
2.1 Configure a Dedicated SSID and VLAN for VoIP:
- Create a separate SSID and VLAN exclusively for VoIP traffic.
Navigate to:
Site-wide > Configure > Firewall > Interfaces
Then add the VLAN interface for the VoIP traffic.
Then create the SSID by navigating to:
Site-wide >
2.2 Limit the Number of SSIDs:
- Maintain fewer than 3 SSIDs to minimize wireless traffic overhead.
2.3 Select the 5GHz band & Enable U-APSD:
Navigate to:
Site-wide > Configure > Access Points > SSID Advanced Settings
- Avoid the congested 2.4GHz band.
- Disable band selection to prevent unwanted band switches by IP phones.
- Ensure that features like L2 isolation and guest networks are disabled to facilitate VoIP communication.
- Activate U-APSD (Unscheduled Automatic Power Save Delivery) only on the SSID dedicated to IP phones.
- U-APSD prevents phones from entering sleep mode during active calls.
- If smartphones are used for VoIP, we recommend to leave 802.11k/v & 802.11r disabled
- Enable 802.11k/v for IP phones frequently on the move.
- Enable 802.11r if phones require WPA2-PSK or WPA2-Enterprise for faster roaming.
- Remember that some phones does not support 802.11k/v and 802.11r which could cause issues in your network.
2.4 Implement Rate Limiting:
Navigate to:
Site-wide > Configure > Access Points > SSID Advanced Settings
- Enable rate limiting on SSIDs not dedicated to VoIP.
- Assign unlimited upload/download speeds for VoIP.
- Allocate 5 Mbps upload/download for office services.
- Limit guest services to 1 Mbps upload/download.
For Office WiFi:
5 mbit/s Download + 5 mbit/s Upload
For Guest WiFi:
1 mbit/s Download + 1 mbit/s Upload
2.6 Optimize Wireless Radios:
- If you need 2.4GHz radio for WiFi, please set the max output power of the 5GHz radio 6~8 dB higher than the 2.4GHz radio.
Navigate to:
Site-wide > Configure > Access Points > Radio Settings
- Schedule Dynamic Channel Selection (DCS) outside of office hours.
2.7 Enable Smart Steering:
- Activate Smart Steering and configure the following thresholds:
- Station Signal Threshold: -76 dBm
- Disassociate Station Threshold: -80 dBm
- Station Retry Count: 2
2.8 Survey Client Signal:
- Aim for an ideal signal strength of IP phones better than -67 dBm.
- Re-evaluate AP deployment if stationary IP phones show worse than -67 dBm.
Section 3: VoIP Configuration on Nebula Switch
3.1 Set Quality of Service (802.1p) for VoIP Traffic:
Navigate to:
Site-wide > Configure > Switches > Switch Settings
- Configure 802.1p for VoIP traffic on Nebula switch.
- Then configure Voice VLAN with the OUI of the IP phones
For example, if you have an IP phone from Company A with MAC address 00:0a:95:9d:68:16, you can enter OUI 00:0a:95 to match all devices from Company A.
3.2 Switch Port Configuration
- Specify settings for Access Ports (connected to IP phones/PC) and Trunk Ports (connected to AP/gateway).
Section 4: Application Layer Gateway (ALG) for VoIP
4.1 Understanding ALG for VoIP Phones:
- An Application Layer Gateway (ALG) is a critical component in facilitating VoIP communication over a network.
- ALG helps VoIP phones establish and maintain connections by dynamically translating network addresses and ports.
- ALG is essential for handling the signaling and media streams used in VoIP protocols, such as SIP (Session Initiation Protocol) and RTP (Real-time Transport Protocol).
4.2 Configuring ALG in Your PBX:
- Access your PBX (Private Branch Exchange) configuration settings.
- Locate the ALG or SIP ALG option in your PBX settings.
- Enable the ALG feature to ensure that your PBX can intelligently manage VoIP traffic.
- Configure ALG settings as necessary, including specifying the protocols to monitor (e.g., SIP and RTP).
4.3 Caution: Setting UDP Session Timeout:
- While configuring your network for VoIP, be cautious about the UDP Session Timeout setting.
- Setting a UDP Session Timeout that is too high (e.g., 300 seconds) can lead to an excessive number of active sessions in your network.
- Too low UDP Session Timeout setting can cause disconnections and other issues
- Recommended UDP Session Timeout is 60 seconds
- High session counts can strain network resources and potentially impact VoIP performance.
4.4 Rebooting IP Phones:
- After enabling ALG and making any relevant network configuration changes, it is recommended to reboot your IP phones.
- Rebooting ensures that the phones establish new connections and apply the ALG settings correctly.
After successful VoIP configuration, please reboot your phones.
Note: PDF can be found attached at the bottom of this article.