Service Centre Time Stamp (TP-SCTS)
The TP-Service-Centre-Time-Stamp field is given in semi-octet representation (each semi-octet consists of two digital decimals), and represents the local time in the following way:
E.g.: 0x99 0x20 0x21 0x50 0x75 0x03 0x21 means 12. Feb 1999 05:57:30 GMT+3
Field Length Description Year 1 These semi-octets are in "Swapped Nibble" mode Month 1 Day 1 Hour 1 Minute 1 Second 1 Timezone 1 Relation to GMT. One unit is 15min. If MSB=1, value is negative.
Swapped Nibble presentation BCD code where nibbles within octet is swapped. E.g.: 0x31 Represents value of 13