How long is shortly?

[IAmATraitor]

Missed an important call and was left a voicemail to say they’d call me back shortly. It’s been over an hour and still no call back 😩

As long as a piece of string

Usually, that same morning or afternoon. However in my experience of my Ex's family from South Wales, - never. 'I'll do it now' meant I'll think about it in the next few weeks and may do it in the 6 months after that, or I may not. Shortly was not in their vocabulary.

Probably after they've done the next couple things on their to do list.

For me depends on what it is. Could be half an hour, could be never.

If someone was to leave me a voicemail saying they’ll try again shortly I’d think anytime during typical working hours.