subject: Collecting Call Records For A Telephone Management System [print this page] Collecting data reliably for telephone management has particular challenges . It is a separate technology with its own skill set, and is generally not given the attention it deserves. Unreliable data collection produces useless reports.
Each call data record CDR has a real value as it contributes to the accuracy of the Telephone Management system as a whole. If call records are lost the accuracy of reports suffers as a consequence.
A PBX outputs CDRs by one of three methods, IP data, Serial data and as a file. Each format must be handled very differently.
Serial data:
Using an RS232, the specification limits the cable length between the sender and receiver to 15 meters. In reality this can be much further, and can often work up to distances of 50 meters. However for reliable transfer of CDR we should stay within the recommended limitations.
Via IP
A PBX may produce call records and simply drop them onto the network in addressed packets. This method has no service guarantees at all. Taking this method to the extreme , it is possible to transport addressed packets over the Internet however, with valuable data, this is unreliably and not recommended. Even data transported over an Intranet in this manner may suffer from packet loss and therefore be useless to the Telephone Management system on arrival. A second method uses hand shaking between the devices to create dependable data transmission.
File:
Usually found on server based PBX, for example Asterisk, the PBX writes CDR to a file in a shared directory, where the Telephone Management system can access the data.
By definition, serial and IP data need additional equipment to ensure reliable collection of CDR. Several companies offer a solution for this in the shape of a Call Buffer. A call buffer device, normally located technologically close to the PBX receives the CDRs, stores and forwards them safely to the Telephone Management application.
Types of Data Collection Device
Serial data in - Serial data out. The device receives call records at a particular baud rate store the data until the host application is ready to receive it, then forwards it a baud rate suitable to the host.
Serial data in - IP data out. We use this device to receive serial and change it to IP for transmission over a local area network.
Internet enabled device. This data collection device will receive either IP or serial data, store it and then send it to an Internet based telephone management service . The device uses secure protocols to ensure dependable data delivery.
Data collection devices come in the form of either a solid state ultra reliable purpose built box, or can be a software program running on a PC within the client environment.
Buffer vary in price, call buffers start at around $200 per unit and go up to $500.
