Why can’t I register my VoIP device?

SIP registration failures are usually caused by incorrect credentials, SIP ALG, firewall rules, NAT behavior, or devices using the wrong proxy or transport.

How registration works

When a device registers, 2talk authenticates the SIP username and password, then stores the public IP address and port used by that device. Incoming calls are sent back to the last successful registration address.

If a router or firewall closes or blocks that path, the device may appear unregistered or incoming calls may fail.

Check the basics

• Proxy: plus.2talk.com
• Username / Auth ID: Full 2talk phone number
• Password: SIP password for the number
• Transport: TLS 5061 recommended; UDP 5060 supported
• Registration expiry: 180 seconds, if configurable

Recommended fixes

• Disable SIP ALG: SIP ALG often rewrites SIP packets incorrectly and can break registration or inbound calls.
• Use TLS: TLS on port 5061 can prevent SIP ALG from modifying signaling.
• Enable keep-alive: Keep-alive helps maintain the NAT path through your router.
• Restrict firewall access: If forwarding SIP ports, limit access to the 2talk SIP range 27.111.12.0/24.
• Check duplicate registrations: Avoid registering the same number on multiple devices unless the service is designed for it.

When to use port forwarding

Port forwarding is usually not required for basic SIP registration. If your network requires it, forward only the needed SIP traffic to the device and restrict the source IP range to 2talk.