VoIP - What is the Problem?Written by E. B. Randall
In beginning, when Internet Protocol was first designed, no one was thinking about possibilities of sending audio and video. Real time communication was not an issue.
Perhaps greatest single problem is that Internet Protocol (the IP part of VoIP - Voice over Internet Protocol) wasn't designed to ensure that packets are delivered in correct order. When information is transmitted using IP, data is broken up into information packets, each of which is sent separately. The correct sequence of packets is part of information in each packet, but nothing specifically exists to make sure that packets are delivered, and, therefore, received in proper order.
Now this isn't usually a significant issue for web pages, email, etc. Why? Because these aren't real-time applications. Audio and video however, especially live audio and live video are definitely real-time applications. For a real time conversation to work, packets have to arrive - pretty much in order and also within certain time limits.
The first, and one of major challenges then, is to restructure incoming packets into correct order and to somehow cope with lost and/or trashed packets. Face it, internet does not provide a quality of service guarantee. If enough packets are lost, an audio or video stream rapidly turns into a useless mess. While packets can be resent - standard way lost/trashed packets are dealt with - real time communication means that you just can't wait around forever. After a certain time, it's simply too late to maintain a coherent stream.
What we've seen over last few years is a gradual and now nearly explosive growth in use of VoIP, and streaming audio and video. The reason is decline of dial-up and growth of ISDN, DSL, ADSL, cable and other high speed, high bandwidth access modes. Bandwidth is answer to most of problems posed by IP. End-to-end high speed links can ensure high quality sound. The sole remaining problem is latency.
Mobile devices securityWritten by Mike Ber
As this security solution is not such a great idea, other companies have researched, and finally found a new way to prevent cell phones and PDAs theft. This method permits to remotely disable up to four different tasks of a stolen cell phone or PDA, rendering it inoperable. But at same time data contained in device are locked. The beauty of this option is that unit is not damaged in any way - full functionality and data can be easily restored if device is recovered. Thus, device is useless to thief, but it can be reactivated and restored if it is recovered and returned to its rightful owner.
Another new security breach has been encountered this year when reports were received about a backdoor Trojan horse program that can take control over a mobile device. This is first known backdoor Trojan horse for PDAs. The subject program, identified as Backdoor.Brador.A, attacks PDAs running Windows operating system. And like all backdoors, it cannot spread by itself. The Trojan arrives as an e-mail attachment or can be downloaded from Internet. Also, it has a complete set of destructive functions characteristic for backdoors. After it is installed, this small program is activated when PDA is restarted and begins to look for a remote administrator to take control of device. Security specialists claim virus was written by a Russian virus coder since it was attached to an e-mail with a Russian sender address and contained Russian text. Fortunately, Trojanís threat control and removal was rated as "easy".
The important thing about this virus is not number of devices affected, because this number is very small, but fact that this is first one that appeared on "market" is considered to be very important. We have to admit that it is hardly surprising that viruses have found their way to mobile devices. This is natural trend. Where technology goes, viruses will follow. As new technology shifts into mobile market, these threats will move in that direction also. The specialists from Kaspersky Labs claim they were expecting a virus attack on a PDA, due to latest attacks against other mobile devices. Now, PDA users look at a real danger and it is a well known fact that interested intruders will grab chance to attack PDAs and mobile phones in near future. Virus threats development for mobile devices is passing through same stages as one for desktops.