Minimally more data. A normal alpha character is 8 bits (1 byte) long. Standard emojis are encoded in UNICODE. There are a couple of versions of UNICODE, but the most used one us UNICODE-4, meaning that a UNICODE representation of a character can be 32 bits (4 bytes/characters) long. But a byte is a byte (and an emoji is emoji) whether it is on a cell phone or an internet line from your ISP. An emoji is going to be 4 bytes long no matter what. Cell phone doesn’t matter. The ISP person was (a) full of shit, or (b) lying to you, or© utterly ignorant.