September 2008
Intermediate to advanced
550 pages
18h 10m
English
Content preview from VoIP Voice and Fax Signal Processing
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19.2 VoIP ON PC ADD-ON CARDS
VoIP is also supported by PC add-on cards. These cards typically have PCI interfaces. The VoIP voice processing is performed by the PCI cards. In most of these systems, VoIP signaling and networking functions are processed directly on the PC main processor. PC-based add-on cards may support up to several hundred telephone lines depending on the capabilities of the card. At the time of writing, PCI cards with multiple FXS, FXO, and even Quad T1/E1 interfaces were available as commercial products. Most of these add-on cards will need extra supporting software like Astrek [URL (Astrek)] or proprietary software running on a PC to complete the calls. PC-based voice applications, PCI, and compact PCI cards are discussed in references [URL (NMS-Access), URL (Sangoma)].
19.2.1 PC Add-On Cards for VoIP Instruments
PC add-on cards are extended to PC-based VoIP voice quality measuring instruments. The same telephone interfaces on the PCI cards are used for voice quality instruments. PC and measurement software measures voice quality instead of working as a VoIP gateway. PCs are modified to meet different instrument form factors and are used as complete instruments with these add-on cards. This architecture is scalable with appropriate add-on cards [URL (NMS-Access)]. In these instrument applications, the processor inside the computer will perform major computation tasks along with other user applications.
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