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If your carrier doesn't allow 10 digit dialing for local numbers, you are probably pretty annoyed that you can't just hit the redial button on those missed calls. It's possible to rewrite these dialed numbers in your phone system, but I wanted to do this on my Cisco 7961 IP …
Posted on in voice
Although Cisco now markets these phones and ATAs via their Small Business line, I still think of these devices as being Linksys. Although the software that Cisco provides for these devices comes with an upgrade executable, it is only for Windows operating systems. I have found that the easiest way …
Posted on in voice
Protocol Basics
Layer: Application
Transport: <acronym title="Transmission Control Protocol">TCP</acronym> or <acronym title="User Datagram Protocol">UDP</acronym>
Port(s): 5060, 5061
RFC(s): 2543, 3261
SIP is by far the most popular protocol used in VoIP communication today. SIP was designed as a …
Posted on in voice
If your PBX is Asterisk based, you need to subscribe to the asterisk-announce mailing list. This is where Asterisk developers post information regarding new releases and security updates for all versions of Asterisk. If you were on this mailing list, you would know that two recent security alerts (see below …
Posted on in voice
During a recent project, I was asked to configure a Linksys SPA942 4-Line IP Telephone to work with Asterisk in an medium-sized office environment. Since this phone was going to be one of many used in a corporate environment, I decided I would need one master configuration, and then individual …
Posted on in voice
When using Asterisk and a remote bank of <acronym title="Primary Rate Interface">PRI</acronym>s (or any other form of <acronym title="Public Switched Telephone Network">PSTN</acronym> connectivity for that matter), you may encounter an issue known as hairpinning. Hairpinning describes what happens when a call coming from …
