I'm not with Optus anymore, so unfortunately I can't answer your question re drop outs. I used to use a Wifi booster in my home to ensure a strong signal throughout the house.
I still have the modem that fixed my number display problem, and I'm happy to try to get it to you (or anyone interested) if you're in Sydney metro. Let me know if you want it. Otherwise I will be sending it to eletronic recycling once I get a chance.
I'm still getting no ringing tone when I dial using the 1832 prefix - so I have no idea whether the phone is ringing at the other end or not. This issue is in excess of 12 months old and Optus appear not to have the expertise to fix it.
Also, you mention you're getting 'like 15 dropouts a day'. Are you actually getting 15 dropouts a day, or are you only 'like' getting 15 dropouts a day - I'm confused.