Phone calls and sms'es are for free while data is expensive nowadays due to the increased demand for data. The operators earn their profit by taxing the data, while there is little to earn on being competitive on phone calls or SMSes nowadays.

It used to be opposite, first time I had a phone I spent really lots of money on SMS'es until I discovered they were bloody expensive! Some few hundred bytes of data, that ought to be almost for free to send, right? :-)