Port 2000: Cisco SCCP / MikroTik btest
Port 2000 is used by Cisco IP phones (SCCP) and by the MikroTik bandwidth test server.
What runs on port 2000
Cisco's Skinny Client Control Protocol runs on TCP 2000 between IP desk phones and the call manager. MikroTik RouterOS has a built-in bandwidth test server that also uses port 2000. Some firewalls also show 2000 as open because of how they handle Cisco phone traffic.
On a home network
MikroTik routers can run the bandwidth test server on 2000, and small offices with Cisco phone systems use it. Typical consumer devices do not.
If port 2000 is reachable from the internet
A MikroTik bandwidth test server reachable from the internet can be used by others to push traffic through your connection, and it confirms the device is a MikroTik to anyone scanning. A call manager exposed on 2000 invites toll fraud attempts. Neither needs to face the internet.
How to check whether it is open on your network
On MikroTik, check Tools, BTest Server and disable it or restrict it by firewall rule. An outside scan of your public address shows whether 2000 answers.
To find out whether port 2000 is open on something in your home, and whether the internet can reach it, the app scans your Wi-Fi from your phone and checks your public address from the outside. It says what it checked and what it could not. Get RECON for iPhone — one-time purchase, no account, nothing leaves the device.