Abstract: A quality of service (QOS) server gathers information in relation to transport introduced delays and obliterations of so called real-time protocol (RTP) signal streams which are used to packetize signals of synchronous signals origins, for example origins such as telephones and raster scan apparatus, for transport via the IP network. The QOS server is able to provide recently gathered QOS information about a requested call, apriori the actual call set up. In an example of a PBX call centre, an automatic dialler is coupled with a QOS server and in relation to endpoint and route selected data, determines if an IP telephony call should proceed, contingent upon the probable QOS being sufficient, before a call controller initiates a call set up.