With threads like a recent one about the BBC on how organisations get it wrong when giving call costs it's good to report those that get it right. I saw this today:

http://www.visitleevalley.org.uk/en/content/cms/nature/gardens-heritage/myddelton-house-gardens/

"*Calls to 03 numbers cost no more than a national rate call to an 01 or 02 number. This applies to calls from any type of line, including mobile."

As that fails to mention inclusive calls, I say they still have room for improvement.

allegro wrote on Mar 2^nd, 2019 at 12:29pm:

"*Calls to 03 numbers cost no more than a national rate call to an 01 or 02 number. This applies to calls from any type of line, including mobile."

Unfortunately they haven't actually got it entirely right as Ofcom General Condition 14 that mandates 03 being charged at geographic rates unfortunately only applies to UK telecoms providers and certain naughty non UK phone operators are still charging calls to UK 03 numbers at way higher prices than calls to regular 01/02.  This is especially true of budget telecoms providers based outside the UK

Orange Spain were a particularly bad case in point where they used to charge 03 numbers at the same rate as UK 09 adult services lines at about 2 Euros per minute.  I emailed to CEO level but still they didn't change their practice, even though their Spanish mobile competitors weren't doing this.  What has happened since the EU Roaming Directive came in I don't know as clearly that ought to have forced them to include 03 calls as part of people's UK standard call packages.

So to be completely right anyone making a statement would need to say calls from any UK based phone provider to UK 03 numbers will cost the same as calls to a geographic UK 01 or 02 number.