This object identifies optional start codes used when the MIB object pktcSigDevCidSigProtocol is set to a value of 'dtmf(2)'. Different countries define different caller id signaling codes to support caller identification. When Dual-Tone Multi-Frequency (DTMF) is used, the caller id digits are preceded by a 'start code' digit, followed by the digit transmission sequence <S1>...<Sn> (where Sx represents the digits 0-9), and terminated by the 'end code' digit. For example, <A><S1>...<Sn> <D><S1>...<Sn> <B><S1>...<Sn> <C>. The start code for calling number delivery may be DTMF 'A' or 'D'. The start code for redirecting a number may be DTMF 'D'. The DTMF code 'B' may be sent by the network as a start code for the transfer of information values, through which special events can be indicated to the user. In some countries, the '*' or '#' may be used instead of 'A', 'B', 'C', or 'D'. The value of this MIB object MUST NOT persist across MTA reboots.