Drupal 6 as a call logging system - question about node performance & scalability We currently use Drupal as a Knowledge, communications and assessments system for our call centre agents and it is working great. However there has been a request that this to also handle our call logging. 

We utilise profiles to allow manager roles to check their team members assessment scores and what communications they have read, the idea is that they could also do the same with calls taken.

My concern here is that this will dramatically increase the number of nodes from what we have now (articles, comms etc are all created by our team so nodes will be within the 1000's). 

If we employ Drupal for logging calls this would mean that our 1000's of agents would be creating dozens of call logs per day. This potentially would push nodes up into the 1000000's.

Would Drupal and its node / cck be able to cope with this type of load where 1000's of users would be submitting dozens of nodes simultaneously?
This is quite a subjective question. Your best bet would be to ask on some of the Drupal groups that handle this stuff like Drupal High Performance.

There are so many factors in making a drupal site scale it's hard to list them all.

Pressflow is a drupal distro that is built for scaling, they also have some great blog articles on scaling.