Llamada asesina

Well the other person who left a comment said it was very easy to figure out who had done it from the very start ( even with his limited IQ, he said about himself)...Well I guess I am not very good with summing up plots or figuring things out, because honestly I had no idea who the killer was until the end, and I was really in suspense. This was obviously a made for TV movie, but I thought it was enjoyable and I feel bad that another user would automatically assume that everyone will know from the "get-go": "whodunnit?".... NG