Final answer:
IP relay service is a telecommunications service not mandated by the general public but provided by TRS providers to help the hearing impaired or deaf community communicate via phone.
Step-by-step explanation:
IP relay service is a type of Telecommunications Relay Service (TRS), which is not mandated by the general public but is often provided by various TRS providers. This service allows individuals with hearing or speech disabilities to communicate over the telephone network in a manner similar to those without such disabilities. The correct answer to the fill-in-the-blank question is general public, meaning that IP relay services are not required by the general public but are available through several TRS providers, which offer this service as a way to ensure that communication is accessible to everyone, including the hearing impaired or deaf community.