"Sorry. Gotcha tactics are no substitute for real lawyering."
I am licensed only in Texas. Offering information of a general nature in response to a question is not intended to be legal advice in your state.
First of all, you are not looking at the correct rule or even correct set of rules. But even assuming that the method of service is not completely correct (and I can't tell from your question whether all details were met for electronic service), what could you possibly hope to gain by such a silly technicality? You have the responses, so there is no way you can claim something later on is a surprise and even if your fax is not signed, the judge isn't going to punish the other lawyer for not being as sneaking and hyper technical as you. In fact, you are the one who is going to look bad to the judge for agreeing to service and then trying to welch on your agreement.
You need a real lawyer.
This is not legal advice. You should always discuss the specifics of your issue in person with an attorney. Be aware that there are time limits on all claims that depend on the kind of claim, so do not delay in seeking an attorney.
The fact that you are asking this question makes me worry that unless you hire a lawyer, you will end up getting in trouble with the judge for discovery abuse and, therefore, end up owing your adversary some money. You could suffer the even worse fate of having your pleadings striken, in which case you would lose your lawsuit autmatically.
Litigation is not a game and judges do not tolerate gamesmanship. It appears that you not are not only unfamiliar with the rules that apply here, but also your instincts are leading you in the wrong direction. This commonly happens when people, even lawyers, try to represent themselves because they become emotionally involved and lack objectivity. Effective advocacy requires objectiviity, legal education and legal training and experience. I would guess you are 0 for three on these items.
Anything worth doing is worth doing correctly. Please hire a lawyer before something really bad happens to you.