How to set up multiple cascades of forwarding calls?
1. Log into your account of BAS-IP SIP server.
2. Go to the Virtual numbers section and create SIP numbers.
3. Add SIP numbers to your devices and apps as described here.
4. Make sure that all required devices are registered successfully.
5. Open the Forward tab in your device web interface and click New Forward.
6. Enter your Apartment Number which consists of the floor and room number. For example, 223 indicates apartment 23 located on the 2nd floor. Entering this number on the panel the forwarding will work.
7. Enter the Forward Number (directions for call forwarding) from the SIP numbers you created in Step 2. The number must be in the following format: sip:virtual number@SIP server address.
8. Return to your SIP server account and open the Virtual Numbers tab.
9. Open Forward Settings (Call management section) of the number you used in Step 7.
10. Select if there is no answer forward condition, and set the required time after the call will be redirected.
11. Tick the SIP numbers you want to call simultaneously when the call to the configuring number is done.
12. Save settings.