Author: Pasha Teplitsky

I had a licensing overage I couldn’t explain, so I asked AI to investigate.

I was looking at licensing numbers on a CUCM cluster last week and something didn't add up.

More device licenses consumed than users who should have them. Not a huge gap — but enough to make me dig.

So I asked Claude Code to check every phone's Owner User ID field against who actually controls the device — the controlled-device association in CUCM.

A minute later it came back with 13 mismatches.

10 phones had a blank Owner User ID. A real user still had the device listed as their controlled device, but the owner field was just… empty.

3 more had their previous owners still listed — people who'd left the company. The phones had been reassigned, someone updated the controlled device list, but nobody went back and changed the Owner User ID.

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    Continue reading I had a licensing overage I couldn’t explain, so I asked AI to investigate.

    SIP 100 Trying Response Code for SIP Troubleshooting

    SIP 100 Trying response code is part of the 1XX SIP Response Codes and one of the most commonly used SIP response codes in the SIP stack.

    SIP works on a request-response model and 1xx SIP response codes are there to provide information on the status of network-related processes, SIP 100 Trying is one of them.

    Continue reading SIP 100 Trying Response Code for SIP Troubleshooting

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    SIP 404 Not Found response belongs to the 4xx SIP code group.
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    But, first what is SIP?

    Continue reading SIP 404 Not Found – Understanding SIP 404 Response Code

    SIP Response Codes Explained

    Why don’t we start with some trivia?
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    That said, not all of the HTTP codes are relevant and mapped to SIP response codes, so if you know some HTTP, don’t expect to find them all in this list.
    Continue reading SIP Response Codes Explained

    Cisco SIP Gateway configuration: The Ultimate Guide

    Connecting the Cisco IOS Voice Gateway to CUCM via SIP has been the preferred way to do it in the past couple of years.

    The slowly dying H323 protocol (ISDN based) is not being developed anymore while SIP (HTTP based) became the industry standard for VoIP. So whenever PSTN connection is implemented via an IOS Voice Gateway, the choice should be really between SIP & MGCP.

    This is how it’s done, step by step, using SIP.

    Continue reading Cisco SIP Gateway configuration: The Ultimate Guide