Hunt, drunks are an inconsiderate lot. They're having fun, so surely everybody is going to find them terribly charming and humorous. As LaFemme said, the drunk dialer may have thought you wouldn't be able to tell she was drunk.
It's hard to tell you what to do because I don't know the relationship, or how important it is to you. For most of us, there are some friends we just lose because we no longer drink. The reason is they no longer feel comfortable around us.
I had a friend, a drinking buddy, with whom this happened. When I'd been sober about a year, she showed up at my house around Christmas/New Years, stumbling drunk with her new drinking buddy in tow. They stayed about 15 minutes. I didn't say anything negative to them, but I could tell they were just uncomfortable. I didn't speak to her again until the following October when she knocked on my door about 12:30 a.m. She was just as drunk as she'd been at Christmas/New Years. She wanted me to come to her house and meet her new boyfriend. I already had on my pajamas but was not in bed. I politely refused and didn't say a word about her condition. I have not spoken to her since.
If Drunk Dialer's call made you uncomfortable, and obviously it did, perhaps ask her why she called you. Tell her you'd appreciate her calling someone else when she's drunk . . . unless she needs a ride home or is in trouble. Judge how firm or gentle you make this request by the nature of the friendship. If it's one you're pretty sure will end anyway, go ahead and be firm. If it's one in which you think Drunk Dialer dialed without really thinking, gently try to make her think.
I hope this helps. I would be frustrated, too.
Remember: You can't control what Drunk Dialer does. You can control what you do. You always have the power not to answer the phone.