Thanks heaps! I just tried this and it all worked once I removed that particular portion of the dial plan.
For the benefit of others with this problem, I should clarify that only that particular string (separated by '|') needs to be removed, not the entire dial plan string.
I suppose an alternative fix is to choose another dial-prefix instead of "111" as the trigger for the VOIP line, but since they don't have that many phones it was easier to just change the dial plan on the phones, rather than retrain the users. But this will be taken into consideration for future implementations.
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