Schoene Vorschlaege, aber "auf der Leitung stehen" hat die Bedeutung von "etwas nicht verstehen" (die Leitung ist blockiert, es kommt nicht bei mir an.) Es bedarf nicht notwendigerweise eines Missverstaendnisses. Im E etwa: I am a bit slow today, I do not get it etc.

Typische Beispiele waeren "Entschuldige, ich stehe heute morgen auf der Leitung. Kannst du es mir noch einmal ganz langsam erklaeren?", "Mann! Stehst du auf der Leitung? Es ist gruen! Fahr zu!".

Wenn "got one's wires crossed" daher auch synonym zu "I do not get it" (ohne Missverstaednis/Kommunkationsproblem) gebraucht werden kann, Unterstuetzung fuer alle Vorschlaege. Wenn nicht, dann nur fuer die drei Alternativvorschlaege.

OALD:
get your wires crossed
(informal) to become confused about what somebody has said to you so that you think they meant something else
We seem to have got our wires crossed. I thought you were coming on Tuesday.

Longman:
wire
3 get your wires crossed
to become confused about what someone is saying because you think they are talking about something else

BERTELSMANN Wörterbuch
* Lei|tung [f. 10]
3 Rohr oder Kabel, das Gas, Wasser, Strom o. Ä. weiterleitet [...]
eine lange L. haben [übertr., ugs.] schwer begreifen;
auf der L. sitzen [übertr., ugs.] etwas nicht begreifen

I'm more familiar with "auf dem Schlauch stehen" and "eine lange Leitung haben", both of which, as Mausling explained, refer to a lack of understanding on one side rather than a misunderstanding between two sides. Therefore, I don't support
to get one's wires crossed -- auf der Leitung stehen
However, I do support the alternative proposals -- with [fig.] and [inf.] tags.

Thanks for the responses.

I just included that one because I found it in a bilingual dictionary, and because it has at least the image connection to the telephone wire. It seemed at least marginally possible for the ones in the singular, like 'I (must) have got(ten) my wires crossed.' I couldn't tell from the past threads whether that usage might be a little more common in BE; I personally tend to use this expression in the plural, referring to communication between two people.

But if the consensus is that it's not close enough to recommend, that's fine, my main aim is just to get the English expression in.

Maybe it's a useful tactic to put the most dubious translation in the subject line; at least it triggered two responses. (-;

But seriously, both of you are always very good about responding; thank you yet again.