Port 5060: SIP
Port 5060 is SIP, the signalling protocol that sets up internet phone (VoIP) calls.
What runs on port 5060
SIP handles registering phones and setting up, ringing and ending calls, usually on UDP or TCP 5060. The voice itself travels separately over RTP on high ports. It is used by VoIP providers, office phone systems like Asterisk and FreePBX, and many ISP home phone services. The encrypted form uses 5061.
On a home network
VoIP desk phones, analogue telephone adapters, routers with a built-in phone port, and some ISP boxes use 5060. Many routers also have a SIP ALG feature that rewrites SIP traffic, which is often behind broken calls.
If port 5060 is reachable from the internet
A SIP server or phone system reachable from the internet is scanned constantly by tools like SIPVicious looking for weak extension passwords, and a successful guess leads to toll fraud, with attackers placing expensive international calls on your account. A phone registering outward to a provider does not need 5060 open inbound.
How to check whether it is open on your network
Check that your router is not forwarding 5060 to a phone system unless your provider requires it, and that extension passwords are long. If calls drop or have one-way audio, try turning SIP ALG off in the router.
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