Yes, an iPhone can send iMessages without a SIM card. iMessage is a service provided by Apple that utilizes the internet rather than a cellular network. As long as the iPhone is connected to the internet (via Wi-Fi or cellular data, if available), it can send and receive iMessages. However, you will need to have an Apple ID and be signed in to iMessage for this to work. Additionally, the recipient's device must also support iMessage for successful communication. Keep in mind that while iMessage works without a SIM card, some other features may be limited or require a SIM card for activation.