Network cables UTP are fine, it's SpeakerLink that requires STP leads. Chris

Sorry Chris, but your information is incorrect.
Some environments have low levels of EMI / RFI and therefore can use UTP cables as RFI migration along the CatX cable is not much of an issue to be concerned about.
However, there are some environments that do exhibit high levels of RFI and the use of SSTP (not a typo) is advisable to prevent migration of RFI into the Endpoint where it's best to have low levels of RFI [and as already designed in by Meridian].