Task: Text Completion
Input (English): [header] How to find the number of a blocked call [title] Get an private branch exchange (pbx) account. [step] One option is asterisk, a free, open source software. Another is switchvox. <sep> (A) This will also work better than 200 blackwire. If you buy one, it will work with the same account ($ 0.11). (B) The pbx is considered to be a free exchange. While this service typically does not have much use for a desktop account, it gives you access to many anonymous call accounts. (C) A pbx converts your computer into a telecommunications device and will allow you to manipulate incoming call data to identify blocked callers. [substeps] Before embarking on this method ensure that you thoroughly understand the technical challenge it presents and the potential financial burden it incurs. (D) Without switchvox here you are on better business. No other option is available to get a contact number from an online website.
Output (English): C