 The original intercom KTUs, WECo Model 207, were wired for a single talk link, that is, a single conversation on the intercom at a time.The WECo 6A dial intercom system provided two talk links and was often installed as the dial intercom in a 1A1 or 1A2 key system.The 6A systems were complex, troublesome and expensive, and never became popular.