A dual-mode telephone with a satellite communication adapter is disclosed. According to one embodiment of the present invention, a cellular-type handportable phone is equipped with a connector for the attachment of accessories. This connector provides a satellite communications adapter accessory access to the handset's signal processing resources which may operate in an alternative mode to process signals received from a satellite and converted by the adapter into a suitable form for processing. The processing translates the satellite signals into voice or data, and vice-versa.