The registration and/or use of the Extended Name is free of charge to and is only for the use of subsidiaries, business units or employees of the company or members of the association that is the Domain Name Holder, and is not offered as a service to third parties, or, where the Domain Name Holder is a natural person, the Extended Name is only for the personal use of the Domain Name Holder or the family of the Domain Name Holder, is not offered as a service to third parties, and no fee or other compensation is charged in connection with such sub-delegation.
So you are not allowed to provide either paid for or free sub-delegation to people or businesses outside of those parties covered by the AUP (existing businesses or close family members).
What about for-pay directory services?
You are fully allowed to provide a paying directory service as long as you retain the rights and responsibilities of the domain and do not sub-delegate.
Providing a "concierge service" to update contact information is acceptable within the AUP, whether automated through do-it-yourself front-ends, or manual. However, it is assumed that the data published by you is covered by the normal and regional rules and laws for data protection, and you must have the informed consent of the owners of that data (which, as a for-pay service, is the case) unless the data is already freely available from other sources. This would be a legitimate information service that would not be in breach of the AUP.
What about links to other .tel domains?
Separately, a Non-Terminal NAPTR (NTN, i.e. a .tel link) is a pointer to another (sub)domain, and not a record in itself, which means that it simply points to an external domain over which you have no control, and the responsibility belongs to the owner of that .tel domain. That's the same as having links on a webpage of yours that send the user to another website.