This is an obvious answer, but did you search IEEE Xplorer, or alternatively Google Scholar? Neither returned hits on "epabx autorouting ivrs", but they did return hits with only "epabx".
In IEEE Xplorer, there were only three papers with epabx:
1. The TAD Integrated Crosspoint Array-Application and Performance in Wescom's 501 EPABX
Andersen, T.;
Communications, IEEE Transactions on [legacy, pre - 1988]
Volume 22, Issue 3, Mar 1974 Page(s):279 - 287
2. cdma-2000 for high-speed voice *** data transmission over wireless in a campus environment
Bose, R.; Kumar, R.;
Personal Wireless Communication, 1999 IEEE International Conference on
17-19 Feb. 1999 Page(s):457 - 461
Digital Object Identifier 10.1109/ICPWC.1999.759670
3. A PC based voice mailing system
Pande, A.; Sirkar, K.; Kanade, A.; Gracias, P.; Pandit, N.; Kumar, K.R.; Krishnamachari, H.;
TENCON '89. Fourth IEEE Region 10 International Conference
22-24 Nov. 1989 Page(s):503 - 506
Digital Object Identifier 10.1109/TENCON.1989.176987
From google scholar, it returns 105 references with epabx:
http://scholar.google.com/scholar?hl=en&lr=&safe=off&q=epabx&btnG=Search