The operator set out the change, which took effect on Thursday (1 May), in an email to agents.
The new number is 0333 006 8799. Agents should select option one for pre-travel services, option two for new sales enquiries and option three for group enquiries featuring 10 or more passengers.
Jet2 is also directing a wider range of enquiries, including smaller amendments and queries, to the Manage My Booking section of its trade website.
It follows a concerted effort in recent months to roll out a wider range of self-service options for agents, and the reintroduction of a live chat function.
