business voip

FIND ANSWERS TO YOUR BUSINESS VOIP AND UNIFIED COMMUNICATIONS QUESTIONS

System Status
Support Hours (AZ time zone)
Monday-Friday: 5am-6pm
Saturday: 9am-1pm
Toll Free: (800) 285-7995
Submit a Ticket

How do I identify SIP ALG?

Many of today's commercial routers implement SIP-ALG (Session Initiation Protocol – Application-Level Gateway), with this feature enabled by default. While ALG could help in solving NAT related problems, the fact is that many routers' ALG implementations are wrong and break SIP (including VoIP).

ALG understands the protocol used by the specific applications that it supports (in this case SIP) and does a protocol packet-inspection of traffic through it. A NAT router with built-in SIP-ALG can re-write information within the SIP messages (SIP headers and SDP body) making signaling and audio traffic between the client behind routers and the SIP endpoint possible (or impossible when used incorrectly).

You may be affected by SIP-ALG if you run into these scenarios:

  • One way audio on calls
  • No audio
  • Phones dropping registration
  • Callers go straight to voicemail for no known reason
  • Random error messages when your number is called (e.g. “The caller you have dialed is no longer in service”)

Nextiva SIP-ALG Detector Tool

If SIP-ALG is detected, many routers allow users to disable it.

If you have any questions directly ask an Amazing Service Team member here or email us at support@nextiva.com

Tags: , , , , , ,

Comments are closed.




 
Nextiva Logo

Business VoIP Help Center

phone-icon(800) 799-0600 Sales phone-icon(800) 285-7995 Support
Nextiva is the leader in Business VoIP Services. Copyright 2014 Nextiva, All Rights Reserved,
Terms and Conditions, Privacy Policy, Patents, Sitemap