How to get port number list of EM and isqlplus

You can get your portlist information of enterprise manger or isqlplus or others web services in the location of $ORACLE_HOME/install/portlist.ini.

On my system the output is,
bash-3.00$ cat /oracle/app/oracle/product/10.2.0/db_1/install/portlist.ini
iSQL*Plus HTTP port number =5560
Enterprise Manager Console HTTP Port (THERAP) = 1158
Enterprise Manager Agent Port (THERAP) = 3938
Enterprise Manager Console HTTP Port (arjudba) = 5500
Enterprise Manager Agent Port (arjudba) = 1830
Enterprise Manager Console HTTP Port (arju) = 5501
Enterprise Manager Agent Port (arju) = 1831

But note that the ports that are listed in portlist.ini file were assigned during the installation. This file is not updated if port numbers are changed after the installation.