The reason the landline to mobile/mobile carrier to another mobile carrier cost is high is because of the fee charged by the receiving carrier - so instead of mobile user paying the incoming cost, it's billed by the users telco to the callers telco which is in turn billed by the set rate of the landline (plan). At the moment it's something like 20c/min so they just keep passing on the cost to the caller; that's why call cards aren't much cheaper.