This is a rather non-topic issue, but I can't think of any other place
where people would probably be somewhat extensively familiar with the

To what extent do people use complete all-in-one so-called Customer
Care and Billing Systems, like Portal, Kenan, and similar? Any
particularly good or bad experiences, including comparisons vis-a-vis
purpose-made systems developed in house?

Off-line replies invited/encouraged; if there are indications of
general interest, I'll produce a summary (anonymized upon request) to
the list (gee, how old-fashioned). It would be very useful if you
could include indications of number of invoices produced as well as the
number of different products/items in the system.