This object identifies optional end codes used when the pktcSigDevCidSigProtocol is set to a value of 'dtmf(2)'. Different countries define different caller id signaling protocols 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 DTMF code 'C' may be sent by the network as an end 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.