Don't know what kind of resources you have access to but we just did something way cool with JMS, JNDI, and JTAPI where we pick up the incoming caller id and route it to the person who last worked with the caller along with any info we have on them. When the attendent picks up the phone, the screen starts popping with the caller info.
Blows the callers socks off when the attendant picks up with "Hello Mr. Smith, this is John again. Didn't my advise about halting cat licking work out?"
The only tricky part was starting a message queue poll when the attendant hung up on the previous call and stopping it when he picked up again. Needed a pbx with jtapi capability.