According to other sources, police checked telephone line at whf after Jeremy called them (3.38am), and police found it to be engaged, not the operator (3.42am). Sequence of events, is out of synchronization, I did not think the operator established phone was off the hook until much later on...
If a telephone line is in use or off-hook, one gets engaged tone on trying to call it. This applies to the operator as well. However, the operator can make further checks (including eavesdropping) to discover why the line is engaged. Regarding any "panic alarm call" or any other type of automated call, such calls are brief - they do not tie up the line, as doing so would be dangerous in various situations, as it would prevent normal use of the line. However, if a telephone handset has been left off-hook, the dial tone isn't present and no call can be made, whether by a person or by automation, until the off-hook handset is replaced.
Ann Eaton mentions that Jeremy told her his call lasted about 11 minutes, or so...
Isn't it the case that Ann Eaton mentioned a delay of 11 minutes, but didn't attribute that delay to any specific cause, such as the length of Jeremy's call?
It would be helpful, mike, if you could provide links to the relevant evidence when you quote from it, so that we can easily see for ourselves what you are referring to (or explain that you have the evidence but it hasn't been made public yet).