Sorry but I discovered that changes had to me made to both the following files:
# Generated by Oracle configuration tools.
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
(ADDRESS = (PROTOCOL = TCP)(HOST = db1.somedomain.tld(PORT = 1521))
ADR_BASE_LISTENER = /oracle/u01/app/oracle
I also adjusted the 'tnsnames.ora' file but that wasn't necessary but did clean up DNS a bit when calling the database server. The 'listener.ora' was a must that had to be manually corrected.