The selective call acceptance allows controlling incoming calls by making a list of telephone numbers which you are ready to accept. But incoming calls from subscribers that are not listed are directed to the answering machine by which the caller is informed that you do not accept calls at the moment.
Citel Technologies , A Voice over IP Phone company that provides VoIP Business Phone Systems. Its Main products include EXTender, PBXgateway, Upgraded Hardware Products, PBX platforms etc.