 Digital Equipment worked with both of these companies – one in Canada and one in the United Kingdom – to design and implement CTI data links between their respective products.Both efforts were successful, and systems using PBXs from both companies were shown at the quadrennial CCITT exhibition in Geneva in the fall of 1987.Digital Equipment released its first CTI software products, operating with the Mitel SX-20 and Northern Telecom SL-1 PBXs, the following year.