* For Rotary phone, make sure you have ver 4.0 or higher hardware.
* For pairing, after power up, cell2jack will automatic start pairing within 2 min (don't need press #*#)
* Make sure your hardware is ver 4.0 or higher. (The version is printed on the back of cell2jack).
* Click here to update your firmware

* 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