Just installed SP4 on version 15 pro. All incoming calls were rejected. Added the IP Address to "allow" on the IP Blacklist. Now inbound calls came through but were blocked after about 30 secs. Activity logs show "ACK is not received from sip: email@example.com" which was the same ip address added to "allow" on the IP Blacklist. Had to open system|parameters, find "SEC_IGNORE_USER_AGENT" and remove "voip" from the value section. (I also tried changing the name of the sip trunk to something other than voip.ms but did not work.) Was this an oversite to, by default, block the sip trunk voip.ms or is it intentionally being blocked? Me, personally, I would think that the manually configured SIP Trunk ip address would automatically be allowed and not in any way blocked, especially from multiple parameters?