Basically,
3550 or 3560 that is PoE complaint means is more towards Cisco VoIP Best Practices because the
Cisco IP Phone gets its power from the lan ethernet port it is connected to.
There is also a limitation on how many Cisco IP Phones you can deploy on a Catalyst Switch.
If it draws too much power or you over-provision, some cisco ip phones may not power up.
Here are some URLs to look at it:
http://www.cisco.com/en/US/products/hw/switches/ps628/prod_bulletin09186a0080117169.html
Advanced Deployment of Voice Over IP
http://www.globalknowledge.com/training/coursepdf.asp?pageid=9&courseid=9002&catid=189&met hodid=o&country=United+States
Also,
If you find the latest version of CCNP Practical Studies; there should be an recommended equipment list for all
lab configurations mentioned in the book.
You can download or search for it via torrent try
www.fulldls.com [you must download and install utorrent client first)
I hope this helps