For frequent travelers looking to avoid international cellular charges or simply want to separate work and personal calls, iPhone offers the ability to disable individual lines on a per-phone basis. This feature was first made available with eSIM models introduced in 2018 (the first phone that doesn’t require physical SIM card). Once disabled, lines no longer appear on your iPhone and any existing voicemail messages will be deleted; once turned back on later you can reactivate calls or cellular data that had previously been suspended.
This article was updated on January 2022 after its original version was originally published on September 30, 2016. This version corrects an error and provides more information on deleting a second line from an iPhone.