Adaptations for Hearing Impairment
RelayUK is a phone relay service for those with hearing and/or speech impairments, it works through the RelayUK user typing their message, an assistant reading it out to the hearing person, and then the assistant typing back the hearing person's response for the RelayUK user to read.
Here is a link to RNID's page on what RelayUK is and how to set it up and use it.