I do not understand why SELCAL is not implemented at all ATC units to use it on 121.5. The technology is really simple. (A SELCAL signal can even be transmitted using a smartphone.) Almost all airliners already have SELCAL capability. (Yes, it does work on VHF!) Monitoring 121.5 continuously over Europe has become counterproductive and nearly impossible to maintain. SELCAL can be the solution! https://www.pprune.org/atc-issues/577965-why-isn-t-selcal-used-contact-us-121-5-a.html