${ANI2} * The ANI2 Code provided by the network on the incoming call.
(ie, Code 29 identifies call as a Prison/Inmate Call)
${CALLTYPE} * Type of call (Speech, Digital, etc)
${CALLEDTON} * Type of number for incoming PRI extension
i.e. 0=unknown, 1=international, 2=domestic, 3=net_specific,
4=subscriber, 6=abbreviated, 7=reserved
${CALLINGSUBADDR} * Called PRI Subaddress
${FAXEXTEN} * The extension called before being redirected to "fax"
${PRIREDIRECTREASON} * Reason for redirect, if a call was directed
${SMDI_VM_TYPE} * When an call is received with an SMDI message, the 'type'
of message 'b' or 'u'