Differences between SIP and IAX for your Asterisk Installations

Today VoipSupply is running a contest about IAX vs SIP because of a new phone launch that supports IAX (finally!).

So, we thought we'd go over a couple of the differences of SIP and IAX and why IAX may suit your needs better.

IAX:

• Only one port needed on firewall
• Works much easier with NAT environments
• Smaller network footprint
• Out of Band DTMF for ease of use
• Created by the Asterisk Team (well supported)

SIP:

• Standard Protocol
• Works with not only Asterisk
• Great if you're not NATing
• Well Supported
• Higher Bandwidth usage than IAX
• Can be a problem with DTMF sometimes

Those are pretty much the bare facts about SIP vs IAX. We're not out to start a war between which one is better, obviously both have their benefits and disadvantages. For us, we like using IAX with any remote office for trunking purposes or for external lines behind firewalls we don't control. For inside the office, we opt for SIP as much nicer phones are available with this protocol.

Which do you prefer?

Don't forget to check out the contest from VOIPSUPPLY while you're at it.