Yeah, a lot of us know it well as a descent on the Black Mountains race. Only thing I can say is the climb from the other side is even WORSE.

I suppose should give grid refs for the route.
OS 1;50,000 sheet 161
Start: Field by Hay School 230 421
CP1: Hay Bluff 244 366
CP2: Lord Herefords Knob 225 350
CP3: Capel Y Ffin 255 314. Safety Refuge 2 plus public call box.
CP4: Grwyne Valley road crossing. 248 291. Safety Refuge 3
CP5. Pen Y Gadair Fawr. 229 288
CP6: Waun Fach. 215 299
CP7. Grwyne Fawr Resevoir 227 312
CP8: Twyn Talycefn. 223 323
CP9: Rhos Dirion. 211 334
CP10: LHK 225 350
CP11: Hay Bluff 244 366
Finish: Field by Hay School 230 421

In terms of comms, I would hope Safety Refuge 1 at Gospel Pass would have line of sight mobile comm to Hay.
SR 2 at Capel Y ffin has a public payphone.
My concern is SR 3 at Grwyne. I'd be surprised if any mobile service works there.
Ideas anyone?