Selfitem.SendTaskDescription for sending out a fax

[FAQ]

Hello all,

we have a requirement where we need to send out a fax at a certain process step.

I was trying to use the method above in a similar fashion as you would send out a email. I changed the type-id to 'F' and added a fax number to the addressstrings container element. 

When the step in the workflow is processed it resturns the errors
- workitem 000003760086: 000003760086 method SWW BI EXECUTE S cannot be executed
- Document could not be sent

Is anybody able to explain how this method is used properly for faxing and where the source of error might be?

Thanks a lot,
Tom