Why You Should Disable SIP ALG on SmartVox VoIP Service
What is SIP ALG?
SIP ALG (Session Initiation Protocol Application Layer Gateway) is a feature found in many routers that aims to assist with the traversal of NAT (Network Address Translation) by inspecting and modifying SIP traffic. It may also be called “SIP Passthrough” or sometimes simply “SIP” on some router screens related to performance or network.
Why is SIP ALG Enabled by Default?
SIP ALG is often enabled by default on routers to help manage and simplify the setup of VoIP services. The intent is to help ensure that SIP traffic can traverse NAT without issues.
Why Should SIP ALG be Disabled on VoIP Networks?
- Interference with SIP Traffic: SIP ALG can modify SIP packets in unexpected ways, leading to corruption or alteration of the SIP headers, which can result in call setup failures, dropped calls, or other call quality issues.
- Compatibility Issues: SIP ALG can cause compatibility problems with certain VoIP equipment and services, particularly those that already handle NAT traversal internally. This redundancy can create conflicts and degrade service quality.
- Difficulty in Troubleshooting: When SIP ALG modifies SIP messages, it becomes challenging to diagnose and troubleshoot VoIP issues. Disabling SIP ALG can provide clearer, more consistent logs and packet captures.
- Performance Degradation: The processing overhead of inspecting and modifying SIP packets can lead to reduced performance and increased latency, negatively impacting call quality.
- Security Concerns: Modifying SIP packets can introduce security vulnerabilities, as it might expose sensitive information or allow unauthorized modifications to the SIP traffic.
How Can I Disable SIP ALG?
- Router Settings: Access your router’s configuration interface, usually through a web browser, and look for the SIP ALG setting. This is often found under advanced settings, firewall, or NAT configurations. Disable the SIP ALG feature and save your changes.
- Consult Documentation: Refer to your router’s user manual or the manufacturer’s website for specific instructions on disabling SIP ALG.
- Seek Professional Help: If you are unsure about making these changes, consider contacting your VoIP provider or a network professional for assistance.
SmartVox Hosted VoIP already makes use of NAT, security, and performance tools that eliminate the need for SIP ALG. In fact, having ALG turned on usually results in many of the negative effects outlined above. Please make sure it is OFF on your network to fully utilize SmartVox Hosted VoIP service.