123.45 is an unofficial chat channel worldwide. You may hear a long chat if two company aircraft are on nearly parallel routes and the flight crew are getting bored and others may chime in, but the most I've ever heard after ten years of cruising around the South Pacific is someone saying "I see you" and the reply was "I see you too, bye..." ATC usually tell an oceanic flight that they may expect to see another aircraft on an opposing route but you're not likely to hear them on a VHF frequency.