You can manually set a preferred SIM card for iPhone X contacts. This article will guide you on how to set a default SIM to use for each of your contacts.
iPhone X is the first iPhone to use a dual-SIM card. When using dual SIM cards, the iPhone X uses the default number for all calls, messages, and data by default. However, there is a way to set your iPhone to use a specific SIM card when interacting with specific contacts. Go through the tutorial below to learn how to set a preferred SIM card for iPhone X contacts.