This is primarily for the UK.
When I was first contesting, our prefered location was Cyrn-y-Brain GW/NW-043. There are several towers there, a BBC VHF Band II FM broadcast, assorted PMR and links, the “shhh don’t mention the military site” and the BT site. I knew it was a BT site partly because of the sign on the compound and partly because some of the contesters worked for BT and had been to similar sites working on landline links. BT used the same tower/building at many sites and as you activate SOTA in the UK, you begin to spot the BT installations.
The other day when researching my up and coming Shetland trip I came across the following website that not only documents the BT sites but lists which other sites they link to. In some cases there are historical pictures of sites in the 50’s and 60’s when Microwave stuff was jolly hard and proper RF engineering.
http://dgsys.co.uk/btmicrowave/sites/mapall.php
What surprises me is just how many of these BT sites I’ve already visited on SOTA exploits. Many more, are known to me as landmarks to look out for when travelling the countryside.
Cyrn-y-Bryn NW-043 => BT Llangollen
Winter Hill SP-010 => BT Horwich
Greyrigg Forrest LD-038 => BT Whinfell Common
See Morris Hill SS-274 => BT Riddingshill
Green Lowther SS-056 => BT Green Lowther
East Lomond SS-198 => BT East Lomond
Craigowl Hill SS-192 => BT Craigowl
Being a sad geek I’ve spent ages wandering around this site, seeing which towers link to where. The sad thing is most of the dishes have been removed now as the Microwave links have been replaced with fibre. That offers much, much bandwidth and doesn’t need expensive to build and maintain hill top sites.
I wonder if they let us amateurs use them as BT don’t seem to have much use for them now?