Cable and Wireless Seychelles and Airtel are the two main telecom providers at the Airport.
CWS SIM Cards can be purchased at their kiosk at the International Terminal at the cost of SR100 or $7.14. You will need proof of ID to purchase the card.
Airtel also operates a kiosk at the airport selling SIM cards for local phone calls. Prices are similar SR100 (local currency) or $7.14. Proof of ID is required prior to buying your SIM card.