You will have to use 4 different checks. ENUM should be catching toll free numbers if it's enabled, but to force free toll free calls I have the following in my dial plan:
Code:
# Pattern Replacement Provider
800 _1800. *${EXTEN} SIP Broker
866 _1866. *${EXTEN} SIP Broker
877 _1877. *${EXTEN} SIP Broker
888 _1888. *${EXTEN} SIP Broker
Just make sure these are ranked before your regular calls.