There have been many attempts to support awareness and lightweight interactions using video and audio, but few have been built on widely available infrastructure. Text-based systems have become more popular, but few support awareness, opportunistic conversations, and mobility, three important elements of distributed collaboration. We built on the popularity of text-based Instant Messengers (IM) by building a mobile IM called Hubbub that tries to provide all three, notably through the use of

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... ons. In a 5.5-month use study, we found that Hubbub helped people feel connected to colleagues in other locations and supported opportunistic interactions. The sounds provided effective awareness cues, although some found them annoying. It was more important to support graceful transitions between multiple fixed locations than to support wireless access, although both were useful.