eSpace U1960 - IP Phone A can call IP phone B, but IP phone B cannot call IP phone A
1. Try to call from IP phone A to other users. - OK
2. Try to call from IP phone B to other users. - OK
3. Try to call from other users to IP phone A. - NOK.
4. Check the service rights of IP phone A with the command:
show subscriber dn A type newservice
After checking the service rights of IP phone A, I found out that IP phone A had the DND service registered in eSpace U1960.
Disable the DND service for IP phone A with the following command:
config modify subscriber dn A operatenewservice del newservicerights dds
For user service related issues, it is best practice to always check the services of the users involved in the scenario on both IP-PBX and IP phone.