Please use fixed AWS IPs and fixed UDP ports
I noticed that TextNow audio calls use random UDP ports for audio calls which explains its lack of reliable reachability. It is quite common for hotspots and many corporate firewalls to allow only specific ports to be used.
I've observed that it consistently signals on UDP port 5090 which is great. Once the other party answers, it negotiates a random UDP port that is relayed through Amazon AWS. This is the problem. No security protocol is going to allow that through.
If, however, TextNow could offer a fixed set of destination IPs and/or destination ports, then it would be much simpler for network and security administrators to facilitate TextNow audio calls through secure networks.
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