Can belletje mean phone call? I could have sworn it did elsewhere
Yes, belletje often means a call for Dutch people.
Could it be that you recall 'telefoontje' with that meaning?
It is a phone call. Bell is completely wrong here.
Both a 'little call' and a 'bell' make no sense in English, certainly in this context!
"What's that you have on your window sill?"
"A bell from the Netherlands."
'a little bell' was rejected.
That's a direct translation and it doesn't fit the context.
A little Dutch bell. This is correct! Ding-a-ling!