The first and only telephone system used in the Comoros Islands is the one working with chip cards, which was supplied by Schlumberger together with the cards, two values that show the OPT logo on a white background: one green, of 25 units, and one red, of 100 units. Several variations of these cards were provided, probably at different times, with various chips and plastic support. The first emission is distinguished by having the matt support and the SC4 chip mounted.
