Axient observes a trend in Australia whereby SIP Trunking is being deployed for Fax. Dialogic recently undertook comparative testing of T.38 and G.711 transport methods over SIP with significant and telling results.
An 'oh yeah we can do fax, that's easy' approach is something that I.T. management needs to be wary of and understand the fine print in order to ensure Quality of Service (QoS).
Two weeks ago, as a trial, one of our Customers, a publicly listed global business with SAP and other key application integrations interfaced with RightFax to a SIP Trunk using G.711 codec as the transport method. The SIP Trunk was provided by their telecommunications partner as a trial service. The QoS issues were so significant that the trial was terminated.
In the past decade, the telecommunications industry in Australia and globally has been undergoing a significant transformation where traditional circuit switched phone systems are being replaced by packet switched IP telephony. IP telephony is a mature technology which has been adopted by Australian companies on a large scale, with the significant majority of new PBX systems being IP based on the internal network. Due to this widespread adoption of IP telephony behind the firewall, many companies are also now replacing costly TDM phone services with a Voice over IP service called 'SIP Trunk'.
Despite the rise of IP PBXs and the emergence of SIP Trunking for voice, there still lie a number of challenges for ensuring that all networks and systems can interconnect reliably using SIP. The SIP protocol does define ways for connecting SIP-enabled IP PBXs and a service providers' SIP-enabled network however it does not address the entire spectrum of interconnection possibilities such as feature sets, security models or addressing QoS issues.
Voice over IP (VoIP) employs a variety of data compression algorithms such as G.711 or G.729a which are designed to save on bandwidth usage but as a result can lose data packets. This is not a major issue for voice calls however a fax transmission requires a high level of data quality to be successful. Therefore conventional fax communications will be impacted using standard VoIP protocols due to network issues like latency, jitter or packet loss.
We are delighted to present hard data from Dialogic that illuminates this subject and ramifications for QoS.
