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Category: Technology

• PHP

If you have studied any engineering career, you should have studied at some point numeric analysis and learned the least-squares method. Just remembering you, the least-squares method aims to minimize the error of the given points when guessing the curve coefficients.

So, if you have some points and you know the order of the equation, this is what you need to know to get the coefficients.

I will write in this article how I used a PHP Artificial Intelligence library to solve any N-order linear equation.

Read more: N-order linear equations curve fit with least-squares and PHP

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Category: Technology

• FusionPBX

Although the word predictive dialer is kind of fussy, some may think it is something that guesses the number you are dialling, but the truth is it is quite another thing. A predictive dialer is just a dialer that has a pre-loaded list of numbers to dial; a predictive it is just because you know what is the next number.

With a little imagination, you can set up an outbound call centre like the one described in the picture.

1. You feed the system with the numbers you are going to call and run the dialer
2. The logged agents take the call and wait
3. The PBX then calls one of the numbers on the list from the first point
4. When the call ends, the Billing for FusionPBX will charge

Read more: Using FusionPBX to setup a Predictive Dialer

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Category: Technology

• FreeSWITCH
• Nagios

Nagios is a software for monitoring, it can virtually monitor anything you want as far as you know how to know how to grab data and you have clear the warning and critical ranges.

Sadly, sometimes after being in production, FreeSWITCH presents orphan calls. An orphan call is the one that it is not active; there is not a conversation passing through it, but it is listed with the show calls command and it might be using resources.

In this post, I will write about how to make Nagios aware of these calls.

Read more: Detecting Orphan Calls on FreeSWITCH/FusionPBX with Nagios

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Category: Technology

• VoIP

Thanks to VoIP we can link remote places and communicate with us at the lowest cost possible. VoIP companies know that, and it is one of the biggest reasons why this industry has been growing.

If you are already educated about VoIP, you have for sure read about SIP and RTP. There are other protocols, but I will focus on these two as they are the most common. The SIP is used to do the signalling while the RTP carriers the sound; SIP has many functions in the VoIP but the main one is related to the INVITE action. The INVITE action is the one responsible for initiating the calls, it carries all details about the call, including the Caller ID Number.

Sadly for use, the SIP does not provide any mechanism to prevent spoofing the Caller ID. This means I could (but I will not) call someone and act on someone's behalf from the Parliament of Canada by setting my Caller ID to 1 866 599 4999. If you do a little search, you will find there are many frauds. Many of them are related to revenue agencies.

The Government of Canada through its telecommunication body, the Canadian Radio-television and Telecommunications Commission, recognizes this danger and it has published a communication about Measures to reduce caller identification spoofing and to determine the origins of nuisance calls.

The CRTC suggests the use of STIR and SHAKEN; however, in my experience, I believe this is not enough and it is just a poor try to cover the real risk. I will explain my line of thinking.

Read more: My Proposal about how to protect your VoIP Customers against Caller ID Spoofing