We recently wrote about the results of Ofcom’s WVMR: https://blog.simwood.com/2021/05/uk-origin-charging/ (and then https://blog.simwood.com/2021/05/uk-origin-charging-delayed/)
As a consequence of this, most carriers in the industry are now introducing surcharges to calls with foreign CLI (with varying rates) or invalid CLI (£2 per minute is the rate many carriers have settled on). We have some recent blog posts which go into further detail if you are interested:
There are some changes that we will make to reduce the risk of us being hit by these surcharges through our network. One area that we have identified within our Partner platform is where customers may have forwarding rules within the PBX. For example, an international CLI could be forwarded, through standard rules within the PBX to an alternative number (let’s say a UK mobile). Potentially, this could attract the per minute surcharge so we will be removing the “preserve CLI” option on forwarding rules as default.