see the reply also
We used the command to got the start handle 0x0023 and end handle 0xffff for service 0xfff0.
[88:33:14:DD:87:6D][LE]> primary
attr handle: 0x0001, end grp handle: 0x000b uuid: 00001800-0000-1000-8000-00805f9b34fb
attr handle: 0x000c, end grp handle: 0x000f uuid: 00001801-0000-1000-8000-00805f9b34fb
attr handle: 0x0010, end grp handle: 0x0022 uuid: 0000180a-0000-1000-8000-00805f9b34fb
attr handle: 0x0023, end grp handle: 0xffff uuid: 0000fff0-0000-1000-8000-00805f9b34fb
The service 0xfff0 is the serial service. characteristic discovery command:
[88:33:14:DD:87:6D][LE]> char-desc 0x0023 0xffff