0800 (and 0808 and 0500) calls are free only from a landline. They currently cost about 20 to 30 p per minute from mobiles. There are proposals to make these calls free from mobiles too, but other changes have to happen first.
084 and 087 numbers have a huge number of price bands. When called from a landline, their cost has to be looked up based on the first 6 digits after the zero. The tariff code and the revenue share part of the call cost can be looked up on Ofcom's web site at
http://www.ofcom.org.uk/static/numbering/s8_code.txt and the total retail call price can be found from the individual landline providers' websites using the tariff code found in the Ofcom list.
The "unbundled tariffs" coming later in 2013 will simplify this process. Each provider will have to declare the profit margin they add on to the price of calling 084 and 087 numbers.
Currently each landline provider adds a fixed amount profit or "access charge" to 084 and 087 numbers. The revenue share amount varies from number to number so the call price also varies from number to number. With "unbundled tariffs", each landline provider will continue to add the same amount of "access charge" for all 084 and 087 numbers, but they will have to state this amount rather than the total call cost (which currently "hides" their profit margin). This will allow you to more easily compare providers.
Mobile operators add a huge profit margin on top of the revenue share premium when calling 084 and 087 numbers. Whether the revenue share is 1 p per minute or 10 p per minute, you'll currently be charged perhaps 35 p per minute by one mobile operator and maybe 45 p per minute by another mobile operator for that call. Numbers with a lower revenue share premium are currently not charged at a lower rate by mobile operators, they just absorb the difference as extra profit. With "unbundled tariffs" they will have to state the profit margin rather than the call cost and they will have to have a fixed margin for all 084 and 087 numbers. This act alone will cause retail prices for calling 084 and 087 numbers to fall when called from mobiles.
The revenue share for 084 and 087 numbers varies according to the actual phone number called. Where a business chooses to use a phone number with a lower revenue share premium for their business, the lower amount will, at last, be reflected in the retail cost charged by both landline and mobile operators alike.
With "unbundled tariffs", your landline provider will tell you their markup or "access charge" is 2 p per minute for 0844 numbers and your mobile provider will tell you the "access charge" is 25 p per minute for 0844 numbers.
The business you are calling will have to declare the revenue share premium or "service charge" that applies to their number. This is somewhere between 1 p and 5 p per minute for 084 numbers and somewhere between 5 p and 10 p per minute for 087 numbers. Businesses will no longer be able to claim that calls are "local rate" or "national rate", neither of which have been true since 2005. They will no longer be able to hide behind unhelpful messages such as "calls from BT cost 5 p per minute, other operators may charge more".
With greater price transparency it will be easier to see which businesses have chosen the highest, and lowest, revenue share premiums.
It will be much easier to see which landline and mobile operators take the biggest profit margins and which take the least.
Many businesses will no longer be using 084 and 087 numbers. The Consumer Rights Directive will force a move to 03 numbers for many businesses. 03 numbers are usable in inclusive minutes from landlines and mobiles. For the small number of callers that pay for calls to 03 numbers, the price will be no more than that for calling 01 and 02 numbers.
The consumer wins.