How to implement call control system for PRI lines

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C#

.NET

Today i come up with in situation where i need to implement system where i need to filter out few number when i call them. My requirement is i have Primary Rate Interface (Pri) network connected to 30 land line telephone sets. With my starting research i am able to find few solution's

Telephony Application Programming Interface (TAPI)
Microsoft Unified Communications Managed
Lync 2013
asterisk

I am able to achieve above motive by refereeing TAPI 3.0 Application development using C#.NET[^] for single connection but still not have any idea about implementation on PRI lines. Asterisk is open source but to implement this we need to tools which are not free. As i am new with this, please give me directions to move on with.