AT&T Co yesterday announced a whole string of enhancements to and agreements on its Number 5ESS public telephone exchange in the Integrated Services Digital networking area. It has agreed with Wang Laboratories Inc to make the communications links of the WIIS Wang Integrated Image Systems compatible with ISDN standards over the AT&T’s switch, with Wang developing the ISDN basic and primary rate interfaces required. It also has a second generation Datakit virtual circuit switch so that ISDN customers will be able to access specified minis and mainframes via mul tiplexed channels at megabit speed. The machines supported by Datakit II VCS are Amdahl Corp’s IBMulators under Unix; DEC VAXes, AT&T’s own 3Bs, Hewlett-Packard minicomputers and Sun Microsystems’ workstations, with IBM’s System/370 mainframes, DECnet architecture and TCP/IP sys tems to be added early next year.