ISS and Heavens-above web page
For the Heavens-above web site, you need to choose:
Radio Amateur Satellites - 24 hour predictions (all passes)
That page will show MANY amateur satellites and their beacon frequencies.
(I can NOTguarantee the validity of any other than the 145.800 for ISS)
Look for an ISS prediction when the MAX ALTITUDE is greater than about 50 degrees for best results - then turn your scanner ON about a minute or two before max altitude happens for your location.
(It is also kind of neat to watch the ISS on those twilight passes when it is visible.)
Sometimes you will hear packets, sometimes voice from either the astronauts OR, when the cross-band repeater is on, you will hear other earth based hams. AND, sometimes you will hear SSTV (slow scan TV).
The last day or so, 145.800 has been silent in my location. Hard to say when the occupants of ISS have the time to monitor/respond. I got lucky the other day and heard someone repeat my call-sign, KG4LBJ, while trying the cross-band.
Uplink, IN THE US, talking to the ISS is 144.49
Uplink for cross-band is 237.800
Good luck (and keep listening)
John