Usage of article: I'm expecting the call from a client in the Netherlands.

[Nessie]

Hi,
Please look at this sentence:

Let me know if the phone rings because I'm expecting the call from a client in the Netherlands

=> There's a mistake in this sentence and I think it's "the call", which should be changed into "a call", but I choose it just because one option must be chosen. I do wonder if "the call" is really unacceptable here. (I think we can still use "the" here to emphasize that very only call)
What do you think?

Regards
Nessie
_________________
... something we never have again, I know... I guess I really really know..

Sorry seems to be the hardest word...

[Molly]

Yes, if unmarked, I wouldn't use the call there. I might here though:

Let me know if the phone rings because I'm expecting the call from the client in the Netherlands.

Mind if you want to emphasise/mark "the", you could:

Let me know if the phone rings because I'm expecting the (pronounced: thee)* call from a client in the Netherlands.

*i.e The one and only, the most important call (salient), the one I have so been waiting for.

[Nessie]

And so you have the same idea as me? which means all these are alright, according to which part we want to emphasize?

a call from a client (any calls, any clients)
a call from the client (emphasize the client)
the call from a client (emphasize the call itself - that only and only call)
the call from the client (emphasize both - that very call from that very client)
_________________
... something we never have again, I know... I guess I really really know..

Sorry seems to be the hardest word...