Walled gardens versus open standards

Some vendors are attempting to create "walled gardens" of closed proprietary content for information appliances, leveraging existing proprietary technologies. However, with the exception of NTT DoCoMo's i-mode, these efforts have been less successful than predicted, due to the willingness of most vendors to work together within open standards frameworks, and the pre-existing widespread adoption of open standards such as GSM, IP, SMS and SMTP.