You are here
Documentation
- InfinityOne
- Infinity Video Server (Beta)
- InfinityOne Work at Home
- Galaxy Mini
- Galaxy Mini - Table of Contents
- Galaxy Mini - Overview
- Galaxy Mini - Server Hardware
- Galaxy Mini - Supported Phones and Devices
- Galaxy Mini - Front and Rear Panel Interfaces
- Galaxy Mini - FXO/FXS Module Installation
- Galaxy Mini - Connecting the Server to the Network
- Galaxy Mini - Activating and Licensing
- Galaxy Expand
- Galaxy Expand - Table of Contents
- Galaxy Expand - Platform and Hardware Overview
- Galaxy Expand - Initial Configuration
- Galaxy Expand - Module Installation
- Galaxy Expand - Reference Architecture
- Galaxy Expand - Common Configuration
- Galaxy Expand - Standalone UCX Server Configuration
- Galaxy Expand - High Availability UCX Configuration
- Galaxy Expand - Local Gateway (Expansion Chassis) Configuration
- Galaxy Expand - Remote Gateway Configuration
- Galaxy Expand - Survivable Remote Gateway Configuration
- Galaxy Express
- Galaxy Modular Hardware
- Servers and Gateways
- Introduction
- Quick Start
- Planning
- UCX Virtual Machine
- UCX Server
- UCX Web-based Configuration Utility
- System
- Fax
- PBX
- Reports
- Accessories
- My Extension
- Security
- Support
- Survivable Remote Gateway (SRG)
- High Availability (HARC)
- UCX Digital Station Module (DSM16)
- UCX M1/CS1000 Media Gateway
- Digital Gateway
- External Gateways and Devices
- SIP Trunks
- How-To Guides
- UCX Applications
- UCX Features
- Answer DN Behavior
- Background Music
- Busy Lamp Field (BLF)
- Global BLF key label change
- Parking Lot Monitoring Solutions
- Call Transfer and Recall
- Call Monitoring
- Call Recording Options
- Dial System Fax
- Dictation Service
- Distinctive ring tones
- Fax to Email
- Group Pickup
- Hotline UCX Configuration
- Hotdesking
- Language prompts
- Long Tones
- Ring Again (Call back)
- Shared Call Appearances
- Set Based Configuration
- UCX MADN Emulation Solutions
- Unified Messaging for M1/CS1000 Users
- User Extension Portal
- Voicemail and VmX Locater
- Voicemail Escalation
- Voicemail Message Indicator
- ZapBarge
- Telephones
- Installation Guides
- Product Specifications
- General Information
- Product Bulletins
- Product Notices
- UCX 6.0 End-of-Support
- UCX 7.0 and InfinityOne 4.0 General Availability
- VPN Security Update Required
- Email Relay Using Gmail Account Fails Due to Bad Credentials
- InfinityOne Release 2.x End-of-Life
- InfinityOne Android App General Availabililty
- E-MetroTel not affected by Log4j vulnerability
- Web-based GUI Security Enhancements
- User Portal Security Update
- Simplified UCX Configuration for Remote InfinityOne Softphones
- InfinityOne Release 3.0 Server General Availability
- Availability of Connection Sharing
- Availability of Automated Cleanup
- Availability of IP Block List Feature
- InfinityOne Release 2.0 Availability
- Digital Station Module (DSM16) Availability
- UCX Software Updates
- Quotations and Ordering
- Nortel Legacy
- Support and Troubleshooting
- Partner Onboarding
- E-MetroTel Business Practices
- Recurring Services Payment Policy
- Product Licensing
- Extension Provisioning Services
- Subscription Services
- E-MetroTel SIP Trunk E911 Registration
- Reseller Responsibilities
- Software Subscription and Warranty Transfer Request
- Return Material Authorization (RMA) Policy
- E-MetroTel Beta Trial Policy
- E-MetroTel Training Expectations
- 9-1-1 Services Agreement (Canada)
- References
Unexpected call failures and registration problems
Introduction
If you are experiencing problems where phones are not registering or incoming calls are failing, then the issue may be that SIP ALG is enabled in your router. The following are a list of issues that you may experience due to SIP ALG:
- One-way audio on an incoming call
- Dead air/dropped call on an incoming call
- Failure to transfer an incoming call
- Unable to put a call on hold or park
- Unable to resume a call or unpark
- Inbound faxes failing
- One phone in a group not ringing
- Phones are not registering
What is SIP ALG?
SIP ALG stands for Session Initiation Protocol Application Layer Gateway. It is intended to prevent some problems caused by firewalls by inspecting VoIP traffic and if necessary modifies the VoIP packets. Many commercial routers have SIP ALG turned on by default.
What is the impact of SIP ALG?
SIP ALG modifies SIP packets, which controls voice calls and faxes. In most cases, SIP ALG is poorly implemented and modifies the SIP packets in ways that either corrupt the packets or removes pertinent information from the packets. Therefore problems caused by SIP ALG can be varied and unpredictable.
How to turn off SIP ALG?
Instructions to turn off SIP ALG is specific to each router. You will need to refer to the manufacturer's handbook for your device.