SONET payload scrambling in IOS and JUNOS:

http://www.cisco.com/warp/public/127/POS/flag_byte.html
http://www.juniper.net/techpubs/software/nog/nog-interfaces/html/sonet-payload-scrambling3.html

7505 to m7i:

interfaces {
    so-0/2/0 {
        sonet-options {
            fcs 32;
            payload-scrambler;
        }
        unit 0 {
            family inet {
                address 172.16.18.3/24;
            }
        }
    }

interface POS0/0/0
 ip address 172.16.18.5 255.255.255.0
 encapsulation ppp
 crc 32
 pos scramble-atm
 pos flag c2 207 <--- 0xCF not 0x16 (22) in this IOS
!
Inuyasha#sh ver | inc IOS
IOS (tm) RSP Software (RSP-PV-M), Version 12.2(18)S5,  RELEASE SOFTWARE (fc1)