IT Answers » SIP

(Cisco VoIP) PGW Softswitch SIP OK SDP towards ACE SBC media address mismatch

Breakmylegs — Wed, 26 Oct 2011 14:59:04 +0000

New Answer by Michael Tidmarsh

Firewalls and SIP trunks, t38 faxing not working

AnchorS — Fri, 07 Oct 2011 15:13:03 +0000

We have installed a voip system from Interactive Intelligence (Indianapolis Oh). We get dial tone from two sip trunks for inbound and outbound calls. Works great. Between sip router, and server, is a firewall. Firewall does not play nice with t38 faxing. Anyone have a similar setup that is working for t38 fax?

NOTE: scary…but fax work fine if firewall is removed. Fortigate support is working on this as well, but I’m not getting a good vibe.

So, I’m willing to change vendors on the firewall, if I can find one.

Running SIP proxy server as a virtual machine

TeachMeIT — Thu, 19 May 2011 19:45:55 +0000

What role does the SIP proxy server play and what issues would we see if it goes down? Can we run it as a virtual machine and have a backup one in another VM?

Long distance monitoring SIP servers and proxies

TeachMeIT — Mon, 16 May 2011 14:41:28 +0000

We have a data center hosting our sip servers and proxies. The location is far from our main office. How can we monitor the servers and the lines?

Carrier SIP trunking

Jaimito — Mon, 25 Apr 2011 18:46:55 +0000

What hardware resources does a carrier need to deploy SIP Trunking Services to current TDM users?

Blocking sniffers from catching SIP/VoIP traffic

TeachMeIT — Thu, 14 Apr 2011 19:11:54 +0000

Can we block wireshark or ethereal from being able to run on our Windows 2003 Active Directory network? We want to block sniffers from catching sip/VoIP traffic.

Cisco 7965 and remote SIP server not working

Chrisss — Tue, 08 Feb 2011 01:10:38 +0000

Hey guys,

I have this very weird problem and I just can’t fix it.. any ideas would be very appreciated!

I have a Cisco 7965 ip phone here on my desk. I have a tftp + sip server running in a datacenter and it seems the phone fetches all the data from the tftp, but can’t connect to the SIP server.

Now here’s the weird thing..

If I run the tftp + sip in the same local network with my cisco phone, everything works perfect! I can call outside and receive calls.
As soon as the tftp or sip is outside (datacenter) I’m having this problem.

To make it even more complicated, I’ve tried with iphone app Softphone, and then the external SIP does work!
I’ve checked and double checked everything and it all looks okay.. so any suggestions what to do? (yes I have changed remote IP’s + NAT settings)

Thanks in advance!

Does cellular routing technology exist?

Crosbycurious — Tue, 07 Dec 2010 05:36:04 +0000

What is the technology that would allow a call from a cell phone to be routed to a transmission device that triggers a loud beeping sound. For example, using a cell phone to call a number that calls a database, and then triggers an external receiver that is attached to one’s keychain for example?

Tool for determining how many SIP proxy servers are needed for installation

TeachMeIT — Mon, 06 Dec 2010 22:06:23 +0000

How can we determine how many sip proxy servers are needed for a new installation? Is there a tool for this?

SIP on Asterisk

Kid1612 — Wed, 25 Aug 2010 02:25:21 +0000

when i make a phonecall between 2 softphone via Asterisk server.
so asterisk server as a registrar server or location server or UA like B2BUA?
i don’t know about it.
please help me.thanks