Communication
One of the biggest management fears of telecommuting is the "out of sight, out of mind" mentality, and for good reason: it is a gross analogy, but trusting an employee to do their job when nobody is looking is akin to sending a son or daughter off to college. They will either responsibly succeed or quickly fail. It is easy to make the promise to over-communicate, but having the right tools at your disposal will keep coworkers informed and a paycheck coming in the bank.
As discussed, a reliable phone is an obvious necessity. If there is not an easy means to get a group talking in conference, though, much of that usefulness is for naught. Ideally, the employer will provide some way to teleconference - be it voice, web-meeting, or some other capability. In lieu of paid services, reliable, free solutions can be found online. It is essential for a group or team to be able to quickly and easily communicate with one another.
When voice communications are not necessary, instant messaging (IM) technology is an enormously beneficial service to a distributed team. It is the 21st century equivalent to popping your head into someone's office for a quick question, but with more subtlety to the interruption. Again, many robust, enterprise-capable solutions are available (Sametime, Skype), but full-featured IM software can be found for free (Messenger, Google Hangouts, WhatsApp, Slack), as well.
The point of this is to make it as easy as possible to make yourself available as a telecommuter. Rather than walk by your cubicle, a manager can see you on IM, or make a quick phone call - anything to alleviate the fear that you are playing Xbox instead of on the job. This is as good a place as any to touch on team collaboration, as well. One employee available and on point is good, an entire team is even better. Different managers will have different styles, but keeping track of what everyone is doing and where progress stands can easily be maintained among a team of telecommuters via any number of online tools. As with IM and teleconference technology, issue and project tracking software comes in many forms, both COTS or freeware. The advent of wikis and cloud storage have also eased the problems associated with collaborative information sharing. These all depend on a capable network and (if applicable) VPN - one should not notice any difficulty accessing a resource from home.