The cost will be in the range of USD2.3 to USD2.5 per minute for the voice calls and 60 cents per SMS.
Anyhow its not an economically fesible for the airlines because of the high cost involved in installing this system. Furthermore the business model consists of different players such as Aeromobile,Imrasat and the Cell phone provider and what ever revenue is generated has to be shared beteen these parties and the airline. So at the end of the day the revenue generated from this service is very low. What the airline gets is that it can enhance its product.
But we have to wait and see how many really want to travel with such airlines offering this service. In this forum itself many people aready stated that they will think twice before choosing Emirates.
Time only says whether In-flight mobile telephony, will have the same fate of Connexion by Boeing a 1 billion dollar project which finally was only worth 150-200 milion.