I have no idea what you want to achieve. Detailed description needed.
Do you mean Sip connection to 3rd party devices?
https://support.ringcentral.com/article/Setup-and-Provision-Deskphones.html
Using the RingCentral Phone for Desktop, you can dial or receive test calls, send and receive test SMS or Fax messages in your sandbox environment.
Download RingCentral Phone for Desktop:
Tip: switch to the "sandbox mode" before logging in the app:
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