I was initially thinking to use a ternary expression but it doesn’t seem to be working with ticket tags:
[=('{TICKET TAG:ENTER PHONE}' == '' ? 'NO NUMBER' : '{TICKET TAG:ENTER PHONE}')]
What that would do is see if the ticket tag is empty and if so print ‘NO NUMBER’. If it is not empty it would display the ticket tag value.
Another thought would be to automatically tag the ticket if no phone number is present:
Event Name: Before Ticket Closing
Custom Constraint: {TICKET TAG:ENTER PHONE} [IS NULL]
Action you’re using to tag the ticket:
Tag Name: ENTER PHONE
Tag Value: NO NUMBER
change:
[<L00><block 1><size 20>{TICKET TAG:ENTER PHONE}</size></block><br/>]<br/>
to:
<L00><block 1><size 20>{TICKET TAG:ENTER PHONE}</size></block><br/><br/>
For readability, I would recommend a more descriptive name for the ticket tag like Phone, Phone Number, Phone No, Phone Nr, etc. I feel it is easier from a readability standpoint when looking at the ticket. YMMV