Articles tagged with sip

  1. Cisco IP Phone: Rewrite Dialed 10 Digits to 7

    Posted on in voice

    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 …

  2. Linksys IP Phone Upgrade URL

    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 …

  3. Voice over IP (VoIP) Protocol Review

    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 (Session Initiation Protocol)

    SIP is by far the most popular protocol used in VoIP communication today. SIP was designed as a …

  4. Subscribe to asterisk-announce

    Posted on in voice

    Asterisk logoIf 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 …

  5. VoIP Hairpinning Issues

    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 …

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