If you want to have your trial proceed, give him the information. The goal is to get the matter resolved, not worry about technicalities in service. Resend it by mail, document his contact with you and document your response. That way if he does not show up in January you have shown that you have done everything possible to get him there.
If you dont and he doesnt appear, you may win. If he later challenges the outcome, and it comes out that he asked you for info and you failed to provide it knowing his address was no good, it will likely be set aside, and you will be back at square one.
There would certainly be no harm in advising the opposing party by phone of the trial date. I would also follow up that discussion with another letter confirming that you verbally notified them as well.