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PDD - Pre Dial Delay

PDD, or Pre Dial Delay, is a measure of the time it takes for a Voice over Internet Protocol (VoIP) call to be established after a user initiates the call. It is the time elapsed between when the user dials the phone number and when the first provisioning response is received. A good quality VoIP route should have a PDD of less than five seconds. This means that the call should be connected within five seconds of the user dialing the phone number. The PDD is an important metric for VoIP service providers because it impacts the user experience. If the PDD is too high, it can cause frustration for users who have to wait a long time for their calls to be connected. On the other hand, a low PDD ensures that calls are connected quickly and efficiently, which can improve the overall user experience. There are a number of factors that can affect the PDD of a VoIP route, including the quality of the Internet connection, the hardware and software being used, and the routing of the call through ...
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BYE delay fraud

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While working on fraud detection and prevention for a number of VoIP providers, I came across a rarely detected, yet creative type of fraud. It is called BYE delay fraud . Let's see what a regular SIP message exchange looks like when we have four VoIP carriers in chain: What is shown above is a typical (yet somewhat simplified) view of SIP traffic exchange within a chain of four carriers. The messages are chronologically sorted so that the first message appears on the top of the diagram and the last message at the bottom. There are two significant moments for this call: t0 - time when the call is answered: the moment we consider the starting time when measuring the duration of the call t1 - time when the call has ended (hangup by callee): the moment we consider the ending time when measuring the duration of the call So if we say that t0 = 3sec t1 = 45sec The duration of the call is 45-3 = 42sec. Since the OK and BYE messages are forwarded between all four providers ...
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Backup

There are two kinds of people: those who do backups and those who WILL do backups. Sincerely, you don't want to live through the nightmares of a broken or compromised system not having a reliable backup of your data. Think about it. What's the worst case scenario? Your critical data gets corrupted. Your business operations stop, and you can't continue until you recover your data in some way. The data your system holds (especially the data stored at your core business component - your softswitch) is critical to your business continuity. This includes (but is not limited to): CDR data system configuration parameters contracts and contracted prices invoices There are three general guidelines regarding doing your backup properly: The backup should be done regularly and automatically The backup location should be not accessible from the backed-up system The recovery process should be documented and the actual recovery drills should be done from time to time L...
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SIP protocol in a nutshell

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At the very beginning I feel obligated to provide a disclaimer: This post contains an extremely simplified case study to give you a rough view of what SIP protocol is used for and what is it's role in your VoIP business. As it is primarily targeted at non-technical people, I reduced the case to a bare minimum, leaving out many details important to make anything technically useful. My intention was to make it understandable by non-tech people wanting to start a VoIP business so that they get an idea about the technical aspect of the whole thing. The core of any VoIP wholesale business is connecting your vendor (your partner who does call termination to destination networks and whom you pay for the traffic) with your customer (your partner who originates the calls to the destination network and pays you for the traffic). The important fact here is - you are the middleman, the traffic flows through your equipment, you charge your customer by the minute of traffic, your vendor charge...
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FAS fraud

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FAS  (False Answer Supervision) is a very common type of fraud in VoIP wholesale business. I'll try to briefly explain what it is, how it works and how to detect it. Let's consider a following scenario. Our company has an interconnection with EvilVoip company. We made an agreement that they will terminate traffic to Nigeria mobile at $0.07 per minute. We sell that traffic to our customer at say $0.09 per minute. So far so good. A call comes from our customer, we route it to EvilVoip, the phone conversation's duration is 60 seconds, we made $0.02 on that call. Everything is fine. Now, EvilVoip gets nasty and greedy, wanting to raise their profit. So they make a little change in their routing so that the calls from our customer (that we send over to EvilVoip) don't get terminated on the target number but instead they end up locally at EvilVoip's custom IVR  that does nothing more than playback a prerecorded message saying something like "Hello? Hello? I can...
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Setting up a SIP interconnection

When you run a VoIP wholesale business, one of your regular tasks is to setup interconnections with your partners , be it vendors (providing termination services) or customers (originating the voice calls). These interconnections are used to send and receive voice traffic between VoIP companies . Nowadays the interconnections between VoIP carriers are based on the SIP  (Session Initiation Protocol). While I'll not be explaining the SIP internals within this post (I'll do it in a separate post), I'll try to briefly describe what happens in a typical scenario when two VoIP wholesale providers establish a SIP interconnection between their softswitches. So a typical workflow would be like this (in this example our/your company is establishing interconnection with a vendor so that we can send voice traffic to them): Our sales rep closes a deal with a partner (let's call him VoipN), they agree the prices and destinations that VoipN will accept voice traffic to (let'...
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Starting a VoIP wholesale business

Starting a VoIP wholesale (or retail for that matter) business can be a demanding endeavour. At first it seems straight-forward: you buy (or rent) a softswitch, organize your NOC (Network Operation Center), connect your equipment to your partners and you are ready to start routing voice traffic buying at one price and sell it at a higher price, achieving profit. Seems simple and, at the end, it is. However, I'd like to share with you my knowledge to give you an impression what starting and running such a business implies. As soon as you start putting things together and start to organise and plan your business operations, you realise that the devil is in the details, be it technical, organisational, financial, legal or other. Your effort heavily depends of your prior knowledge of how everything works in the VoIP wholesale realm. A fantastic fact in this business is that not a single operational process is physically bound to any geographic location. You can setup a company in...
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