The E-30-PT is designed to provide quick and reliable communication in noisier areas. The mic sensitivity is set to a low level until the TALK button is pressed then it is raised to a normal level. In this way the E-30-PT assures that the called partyft. s voice will be broadcast over the speaker. In applications where the background noise can be louder than the person calling a handset type phone is recommended. The E-30-PT features non-volatile memory a built in dialer and intelligent call progress detection for automatic hang-up when the call is completed. The E-30-PT can be programmed to dial up to 5 different numbers on ring no answer or busy and can be configured to dial these numbers until answered.