I asked a C5 driver who stopped off on at EGPK en-route to the Balkans a few years back about the SELCAL situation as they were never appended to H/F readbacks. Answer was that the aircraft were equipped but SOPs forbade their use, so as outlined in previous post, listening watch required. NIGHTMARE!
Most Ocean ATCOs aware of this will always try to raise a RCH c/s thats been out of touch for a while on VHF 'Guard' through the closest aircraft. 9 times out of 10 this solves the problem.
Rgds
T3