Bit of an odd question, and I can't go into all the circumstances why I'm asking this, but anyway: would you find it confusing if a megaphone icon was used instead of a cellphone or telephone icon to represent the action of making a phone call and speaking to someone?
The megaphone does imply speaking out loud to someone, so in that sense it works, but on the other hand, it has no inherit meaning that indicates a phone call.
Would you find this stretched meaning unacceptable, or would you be o.k. with it?