A service processing method and related devices are disclosed. The method includes: receiving, by a mobility management entity (MME), an access request message sent by a user equipment; obtaining, by the MME, indication information; and if the MME has been registered as a short message serving node and it is determined, according to the indication information, that the MME is no longer used as the short message serving node, sending, by the MME, a notification to a home subscriber server (HSS) so that the HSS cancels registration of the MME as the short message serving node.