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:
| 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. |
E.g.: 0x99 0x20 0x21 0x50 0x75 0x03 0x21 means 12. Feb 1999 05:57:30 GMT+3
BCD code where nibbles within octet is swapped. E.g.: 0x31 Represents value of 13