Opt-Outs are handled differently on TF#s than they are on short-codes and re-opting in to a mobile program on a TF# requires a different action. 

Instead of the default system opt-out message sent from on short-codes, when a contact opts out of messages sent on a TF# they receive a special message from the aggregator. 

Default Stop Message for Short-Codes:

You are opted out of {campaign name} and will no longer receive msgs. for info visit {help/stop contact information} msg&data rates may apply. 

Default Stop Message for TF#:

NETWORK MSG: You replied with the word "stop" which blocks all texts sent from the number. Text back "unstop" to receive messages again.

In order to opt back in to messaging on a toll free number, the contact must comply with the instructions provided and reply UNSTOP

This will fully opt them back into receiving messages from that TF# .