Your Yealink SIP-T23P or SIP-T23G phone LCD display shows the message No Service. There is no dial tone, and you are unable to make or receive calls.


Your phone is unable to successfully register a SIP account with our services.


In cases where the phone had been properly working for a long time and is only suddenly afflicted with these error messages, power cycling your network is often able to clear it up.

Other helpful network troubleshooting:

  • Swap out the Ethernet cord connecting the phone to the network for a different one (to see if a faulty cord might be the issue).
  • Is the phone connected to a wall jack? If so, try connecting it directly to a networking device (router or switch).
  • If the phone is connected to a networking device, try plugging it into a different port on the device (to see if a faulty port is the issue).
  • If accessible, review the firewall/router settings and be sure to disable the following:
    • SIP-ALG
    • SPI
    • Firewall

You can also try setting a static IP on the phone, which has been known to help resolve these issues.

No resolution?

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