An alarm system senses alarm conditions on a premises, reports the occurrence of an alarm condition to a remote monitoring facility and for selected alarm conditions establishes two way voice communications with a person at the monitored premises or elsewhere. Multiple modes of communication are available such as public switched telephone (audio or audio modulated data), GSM (cellular audio), GPRS (cellular packet data), GSM/SMS (cellular text), etc. The programmed processor selects the network and communication protocol to rely on data communications if only data reporting is required. When two way voice communications will be required, the processor can select a network (e.g., GSM) that can be used for both data and audio communications.