sdptool search --bdaddr=00:1A:77:ED:D1:97 DUN
Searching for DUN on 00:1A:77:ED:D1:97 ...
Service Name: Dial-up Networking
Service RecHandle: 0x10005
Service Class ID List:
  "Dialup Networking" (0x1103)
Protocol Descriptor List:
  "L2CAP" (0x0100)
  "RFCOMM" (0x0003)
    Channel: 4
Language Base Attr List:
  code_ISO639: 0x656e
  encoding:    0x6a
  base_offset: 0x100
Profile Descriptor List:
  "Dialup Networking" (0x1103)
    Version: 0x0100