I want to select incoming calls based on user input. E.g. by matching the telephone number to the user input number. To get user input number I used Java.
What are the best hardwares supporting to this requirement. I guess this hardware should allow us to call API and get current caller number. Then we can do the selection part using Java. After that we can another API method ans allow that call to proceed.
Let me know about the suitable hardware for this.
You have a number of options depending on how your incoming calls are presented - if you are lucky enough that they are coming in to a PABX which has some form of computer telephony interface (CTI) then you just need to interface your Java app to the PABX (many Cisco, Avaya etc pABX's will support some form of CTI).
If your calls come in on a standard line to a standard phone today, then you can either replace the phone with a simple commercial PABX (if you have the budget) or you can create your own PABX using one of the open source options and some line cards - see the answer to this question for a link to an example line card for the open source Asterix PABX:
https://stackoverflow.com/a/18220055/334402
If you have the option of a hosted VoIP 'telephone line' then it would be worth contacting your provider as they may provide hosted CTI options, saving you the need to get dedicated hardware.