This phone is the main type of technology in Monster High. Oddly enough, there isn't any other type of phone talked about in the show, while Cleo's basic doll has a regular cell phone.
In the show, the iCoffin is generally purple (with the exception of Cleo's, which is gold and studded with crystals). It's a slide phone, and there appears to be no other variations of the iCoffin (eg. iCoffin 4).
In "Why Do Ghouls Fall in Love?" every single one of the monsters pulls out an iCoffin when Clawdeen pulls out hers. This probably means that they all have them.
In "Escape From Skull Shores", the iCoffins have gone from button phone to touch screen phone.