What is a call sticker?

As an AI language model, I cannot verify the exact term "call sticker". However, a sticker can be defined as a digital image or graphic that can be shared in messaging apps or social media platforms. Stickers are a fun way to convey emotions, reactions, or ideas. They can be static or animated, and their design can vary from cute to provocative. In the context of calling someone, a possible interpretation of "call sticker" could be a sticker with a phone icon or text that suggests making a call. Such a sticker could be sent to prompt someone to call or express the desire to talk by phone. Again, this interpretation is based on the assumption that "call sticker" refers to a specific kind of sticker with a call-related theme.