Hey There,
I am a network manager for a K-12 School district and I can tell you what we have done. Basically we only give Ext, Mobility to users that share time between sites all other phones are suppose to either stay in the room or if a teacher is moving from one room to another they can take and swap their phones.
We do not have a huge turn-over in teachers every year but we have integrated our CallManager(6.1) with our Directory tree(Edir here) and that has saved a lot of time in just creating users and assigning extensions in both systems. As for mass changes I really like the new bulk admin tool in CM 6.1, but if you are looking for bulk admin in your directory you can try JRB Utilities, it is a company that makes some fantastic tools for bulk admin of Edirectory accounts and they have branched into Active Directory as well, although I can not give you any feedback on the AD quality. The price is right for $600 though.
Really, the biggest issues we have had here is teacher moving phones to switch ports not assigned in the CER server and ATT assigning the correct lines to our PRI's . We get a lot of calls in that are not for any of the numbers we are assigned as well as 411 directories giving out our PRI line numbers and not the DID's associated with them.
To kind of get back on topic, I import all 10,000 students into our tree every year and then import more as needed from exports on our student system with JRB Utlilities, if you have AD integrated into your CM then this may help with mass changes. You can also do some nice user listings with attributes with JRB U. that can be imported into the CM if need be.
If you are looking at a completely automated aproach then the only thing I can think of would be NSure Identity Manager, but I am a Novell guy so I am sure there are other products out there, I just happen to use this one.
Hope that helps.
