I can't tell from your message if you don't want to be recalled or are trying to get some benefit out of it if you are? I'm going to assume that you don't. If that is the case, the first you'll hear about it is when you get the letter to report. You can check your AKO for army news about MOS's that will be receiving orders to report, but that's the best you can do to my knowledge. It is more likely that you would be placed on the Individual Warrior program in the IRR. That would mean that you would have to report for various training events, muster, etc... as a way the Army is trying to make the IRR more effective. Only 5,000 Soldiers are scheduled to do this in 2007 and the program is not set to go into full swing untill 2013. Being on 20% disability you are unlikely to be called upon to do this soon.
As for contacting your career councilor, you should keep in mind that there are two different types that can contact you. The one from Army HRC is the one that you should worry about if you want to comply with Army standards for IRR soldiers. You must keep the HRC records up to date with info on your address, marriage/dependent status, employment status, and medical readiness. They will contact you about once a year to update these records. If you have any questions contact them through the phone number on their web page. If you are recalled, this is the info the Army will use.
The other group are Army career councilors from retention. If you haven't already, you will be receiving letters from about 40 of them saying you need to contact them about updating your records (apparently they don't have compatible computer systems). Regulations say you need to respond to all Army correspondence, so do so if you want. All these people will be asking the same questions and trying to get you to join a Training unit or go into the Reserves or National Guard. Keep in mind that that's there job and they are evaluated in part by how many people they talk with.
In my experience these people are very shady. They lie about info you need to give them (i.e. your ssn, educational experience, responsibilities as an IRR Soldier, ect...) So you know, as an IRR Soldier you are responsible to show up for muster if called, and keep HRC informed about the things I talked about above so they can know if you are deployable and where to reach you.
Don't get me wrong. I'm not saying to disregard the retention career councilors. I'm just saying that you should know your rights as an IRR Soldier. Specifically that you are not subject to the UCMJ unless you are activated to AD or called to muster. Therefor, if you are told to drive an hour out of your way to meet one of them at their office or one tries to pull rank on you saying you are a stupid PFC (or SSG in my case) feel free to call them on it.
If I am wrong, and you want to reenlist, I would say that your best bet would be to contact one of these retention people and ask about any waivers available for your circumstances. Not knowing your situation, I am surprised that you would be barred from reenlistment for a 20% disability...but I don't know what disability you have.