Don't forget that incoming digits can be translate upto the LDN length:
LDN is 5555
IDC can be from 0 to 9999
Incoming digits will be treated upto 4 digits
In this case, if you receive 10 digits, only the 4 last ones will be treated
LDN is 555
IDC can be from 0 to 999
Incoming digits will be treated upto 3 digits
In this case, if you receive 10 digits, only the 3 last ones will be treated
LDN is 115555
IDC can be from 0 to 999999
Incoming digits will be treated upto 6 digits
In this case, if you receive 10 digits, only the 6 last ones will be treated