For a while we have been using a mix of Jitsi & GS Wave softphones successfully both internally & externally.
Recently we purchased some Zulu licenses & started implementation, but we are unable to get calls from external Zulu clients (both desktop & mobile) to work, Zulu logs in, but calls will not connect & eventually time out. Using Jitsi or GS Wave externally, or the Zulu clients internally all work fine.
We opened TCP port 8002 in addition to the SIP & RTP ports we already had open.
Asterisk Version: 16.6.2
FreePBX Version: 22.214.171.124
Zulu Version: 126.96.36.199
Zulu Client: Latest Stable (one latest alpha)