Voip one way only This topic has 0 replies, 1 voice, and was last updated 21 years, 9 months ago by Patrick. Viewing 1 post (of 1 total) Author Posts 18th February 2003 at 14:38 #23535 PatrickGuest we are using fxs on cisco 3620 and tried to make a call to another phone on a 3640 fxs port, it gives us one way voice only. help please Author Posts Viewing 1 post (of 1 total) The forum ‘Voice over IP’ is closed to new topics and replies.