An R66 Instructor pilot described communication difficulties and conflict with another helicopter during a south shoreline transition through SMO into LAX airspace.

Narrative

I was transitioning south on the shoreline in contact with Santa Monica Tower when a helicopter opposite direction and same altitude was spotted just before we got to the pier. We went right and so did the other helicopter. Tower never mentioned an on coming helicopter. At this time we were already watching a helicopter hovering about 300 to 400 FT AGL near the class B LAX surface just about one half mile in [from] shore. Tower never mentioned this helicopter traffic either. I'm not sure if radar is used in this area or if my communication was unclear to the Tower. I traveled past the pier and requested a frequency change and was granted. I then immediately called LAX Tower for a south shoreline transition. It took five calls and I had to stop just shy of the class B for clearance. I was granted transition and the helicopter I was watching called on LAX Tower frequency and said I wasn't talking to Santa Monica or on frequency. I was on with LAX at this point. I told them I canceled with Santa Monica. The pilot told the Tower he didn't feel it was close either; but wondered why I wasn't on with Santa Monica. I don't feel this was a close call; but feel communication would have helped. I reassessed to keep 123.05 in my back up radio at all times and become more familiar with the area points when I fly in LA. It's very busy when you are not used to it.