* For pairing, after power up, cell2jack will automatic start pairing within 2 min (don't need press #*# or 0000)

* Some of old Rotary may require you to adjust bias sprint position in order to ring. 
 Below is the picture for the "bias sprint" location. Your phone may look different.
 The original web document is listed below for your information.
​https://www.sandman.com/knowledgebase/ring-voltage-tech-bulletin

Since most of the Rotary phone's ringer is based on old technology, it has limited lifetime.
It is quite common old rotary phone's ringer is defected and malfunction.
If your Rotary phone's ringer is malfunction, you can use an external ringer. Click here to see how to install an external ringer