You don't need to wait. Just offer your service on that port and you are done. Why build protocols with shitty networks or shitty admins in mind? You can use m

You don't need to wait. Just offer your service on that port and you are done. Why build protocols with shitty networks or shitty admins in mind? You can use most ports just fine. Multiplayer games show this every day. If those don't work in corporate networks (I include "public" wlan in this) that's fine too. It's not up to you what should be allowed or not in a company setting. ISPs don't block ports just for fun. And if you are big enough like Google or Facebook, just offer a service only on that port. If it doesn't work, show a warning that the customer should complain to the network owner.