According to Madhhab:
6. During the Qurbani season, many farmers sell Qurbani animals to customers over the phone that haven’t seen the animal. Is such a transaction valid in Shariah?
The purchaser should be fully aware of the item that is being purchased. By merely ordering the animal over the phone, one is unaware of the type/ description /size, etc. of the animal that is
being purchased and could even lead to a dispute at a later stage. Therefore if an animal is bought over the phone without the buyer seeing the animal and the transaction is concluded then such a
transaction will not be correct.
Yes, the buyer may phone the farmer and request him to reserve an animal for him. The buyer then goes on the day of Qurbani or a few days earlier, views the animal and confirms his purchase (by
paying the farmer) if he is happy. If the buyer is unhappy, it is not obligatory upon him to purchase the animal. This procedure is in order. The other alternative is that the farmer provides a detailed description of a particular animal over the phone describing the weight, type of sheep, age, etc. The buyer is then satisfied with the description and confirms the purchase. In this case the purchase
will be valid as the transaction has taken place on a particular animal which has been fully described to the purchaser. (Darul Ifta archives)