Advanced Call Manager: I've used this app on Symbian platform and found it the best one for complete call management. It has a powerful rule-based filter that intelligently takes relevant actions provided by you. You can create rules for individual numbers as well as for a group of numbers. It's lightweight and quietly runs in the background. You can create different profiles with a different set of rules and can activate the desired profile at your will. This saves your time giving you the flexibility to apply custom rules at different times during the entire day.
Call Log Manager Pro: This is a powerful call log manager with lots of features. It uses the calendar to log the incoming call details. You can either log a single phone number or can choose selective numbers for logging. It also includes flexible search and export options to find and carry your logged data wherever you want. You can also configure auto-deletion of old call logging data as per your needs. You can also see detailed reports of incoming, missed and received calls in a user-friendly interface so that you can visualize the entire call activity on your phone correctly.
Call Control - Call Blocker: If you're experiencing lots of unwanted and spammy calls and SMS from anonymous callers then this application is a must-have for you. This app has a flexible call and SMS blocker that intelligently detects known blacklisted phone numbers from across the world. You can also create your own blacklist and white-list to create different filters based on these lists. You can set different actions for blocked numbers like hangup, busy and much more. You can also block unwanted callers on the basis of the area code and can also backup your lists both online or on your local data card.
Call Master Key: This is yet another popular call management app for savvy users. It is extremely flexible in call and text routing and can create different rules on the basis of SMS content. It can also block MMS messages coming from selective numbers. Advanced users can also use regular expressions and wildcard characters to create powerful filters. It also supports encryption and password protection for your app-related data. You can also set custom notifications for important events depending on your requirements. This app also supports themes and you can choose one of the available skins that suit or matches with your phone's current theme.
Call Guard(SMS Call Blocker): This application works in invisible mode and supports several modes for flexible call blocking and routing. It can also block outgoing calls so that nobody else can misuse your phone when it is left unattended in public places. You can also password-protect the entire application so that nobody else can change its settings. It also includes a handy widget for the home screen so that you can quickly access the application. You can also use different templates for numbers and area codes to block or divert a group of numbers in bulk.
Call Timer Pro: This unique app is ideal for users receiving large number of important calls one after the other. You can set automatic hangups for selective calls that consume your time unnecessarily. It also gives you the flexibility to configure automatic alerts (ring or vibration) that grabs your attention during the call at different intervals. This greatly helps in closing the call as soon as possible. This application has a very large user base that itself tells the popularity of this useful app. You can also create different types of automatic redials based on different conditions. 
BlackBaller Call & SMS Manager: This is perhaps the most flexible and powerful auto-reply app for SMS and incoming calls. It has lots of unique auto-reply features that are non-existent in other applications. You can also create powerful action-based filters and can schedule them to activate at the specific time of the day. It also has a smart rejection feature that makes the blacklist update process a cakewalk. It also has an event logging module accompanied with password protection facility for the entire application. If you're looking for a powerful answering machine for your Android device, then this application fulfills that need.