Which type of call provides a vague location usually used in large buildings?

The correct answer is PBX calls. In the context of large buildings, PBX (Private Branch Exchange) systems often aggregate multiple phone lines and extensions, which can lead to challenges in identifying precise locations for calls made within that system. When a call is made from a PBX system, the information transmitted to emergency services may just indicate the main address associated with the PBX, rather than the specific location of the caller within the building. This can result in a vague location being provided, which can hinder emergency response efforts in a timely manner.

Other types of calls have their own specific characteristics when it comes to location reporting. VoIP calls typically provide enhanced location information, as they can include specific details associated with the user account. PSTN (Public Switched Telephone Network) calls offer set locations based on fixed telephones but can have limitations in mobility context. Wireless E911 calls are designed to provide more detailed information about a caller's location, as they utilize GPS and other location-determining technologies. Hence, the uniqueness of the PBX system's functioning makes it the right choice for this question.