[VoiceOps] "...but it works with Packet8"

Jim Gurol jim at californiatelecom.com
Sat Aug 21 14:16:01 EDT 2010


I had a similar issues when moving customers from one platform to another.
One had an SBC, one didn't. The one with SBC controller handled these NAT
problems without any tweaks, while the one without the SBC, sometimes needed
tweaking on customer CPE.

Jim Gurol
California Telecom

-----Original Message-----
From: voiceops-bounces at voiceops.org [mailto:voiceops-bounces at voiceops.org]
On Behalf Of Darren Schreiber
Sent: Saturday, August 21, 2010 10:15 AM
To: VoiceOps at voiceops.org
Subject: [VoiceOps] "...but it works with Packet8"

Hi folks,
	We provide a fully redundant VoIP service to our customers where
they hook up two cheap Internet connections to our special little box and we
load-balance / failover across them. We have been running into periodic
issues with SIP ALG and such typical VoIP crippling technologies when
hooking up our equipment, requiring us to get into the client's router and
turn off SIP ALG (or Cisco "fix-up" features). Specifically we have issues
with 2Wire devices, which are very very popular. We've been assuming this is
standard/par-for-the-course behavior.

	 We have a partner who is reselling our service and he has asked me
a few times why our service requires any tweaks at all. He is literally
replacing Packet8 phones with our service. We are utilizing the old Packet8
phones so it is not a model and unlikely a firmware issue. Something we are
doing in our way of configuring these phones is fundamentally different then
Packet8. The reseller feels we should not have to mess with the clients
router. I'm starting to think he has a valid point.

	So, my question is, why does Packet8 work so well behind so many
firewalls? I don't think their Aastra firmware is all that different then
stock Aastra firmware. So my thoughts are:
- They might be using TCP signaling for SIP call setup instead of UDP?
- They might be ignoring the contents of SIP packets and rewrites and using
rather "aggressive" settings on the switch side to figure out routing based
solely on network headers (we use the actual SIP packets)
- They force rport?

	I'm just guessing at this point, but the reseller has a valid point
- we should be able to compete with this directly.

	Let me know your thoughts or if you have any advice on
best-practices for setting up Aastras (and other phones) to behave nicely
across firewalls that have SIP ALG *enabled*. Sorry if this is a lame or too
broad a question. Any tips & tricks you've used are helpful.

Thanks much,

Darren Schreiber
Co-Founder - VoIP, Inc. - (415) 886-7900 www.2600hz.org - Free VoIP Software
www.voipkb.com - FreeSWITCH Trainings

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