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|VoIP storage requirements|
VoIP recording consumes approximately 1MB of storage per minute of phone conversation. In general, most voice-recording systems use DAS, but many allow voice data to be recorded to SAN/NAS storage as well. According to Cara Diemont, marketing director for Data Dimension's Customer Interactive Solutions and managing editor of the firm's "Merchants Global Contact Centre Benchmarking Report," a mid-sized call center handles approximately 10 million calls per year. At that rate, 38,000 calls per workday would generate approximately 154GB of voice data each call-center day (assuming four minutes per call and recording all calls)--or approximately 750GB of voice data per week.
There are some adjunct files that are produced for each phone call as well. These don't amount to much data, but may represent a sizable number of files, considering there may be close to 1 million calls per month, which could quickly overwhelm a single file directory.
Industry statistics indicate that only 1% to 3% of stored voice recordings are listened to during the first 30 to 90 days; after that period, access rates drop precipitously and the voice-recording data should be moved to less-expensive tertiary or archival storage. Of course, it's also possible that many of the recordings can be deleted. How much of the original call volume is retained is a function of your industry and its regulatory environment.
How VoIP works
Telephone data over the Internet uses Session Initiation Protocol (SIP) packets to initiate phone call activity. VoIP data can be recorded directly from VoIP systems, or indirectly using standard IP networking tools to replicate traffic destined for a telephone adapter via an IP or MAC address. In either case, data traffic ends up at a voice-recording system server, which reconstitutes the telephone session from the IP packets and creates a file or database row.
Most systems add meta data associated with a voice recording, such as a time-date stamp, and possibly Caller ID and target phone number. This additional information is crucial for retrieval and processing of the voice recording; it can be appended to the voice-recording database row or be in a separate file directory associated with the voice recording.
Voice recordings have historically been used for quality-control purposes (of phone-based services) and for possible legal proceedings; this is especially true for 911 and other emergency-response center phone sessions. Financial service firms routinely document customer order details in case an order is subsequently questioned. New compliance regulations mandate record retention, but compliance is mainly a function of the content of a record, not its physical form, says Mike Casey, vice president of services development and marketing at Contoural Inc., a technology consulting firm in Mountain View, CA.
Some call centers record all telephone sessions, while others record only certain calls. Calls can be recorded in real-time by a telephone operator simply tagging a call session, or recorded based on the phone number called or activated automatically by other predetermined criteria. David Brandon, senior technical call-center consultant at Forsythe Solutions Group in Skokie, IL, says stress monitoring is one trigger that can be used to identify a voice recording for special archiving; if the stress level is high, the recording is tagged for later human review and stored in a special archive.
There are products that "word spot" a recording, searching for a limited word vocabulary like "stop," "cancel," "halt" and so on. Paul McIntyre, product manager, customer interactive solutions at Dimension Data, says there are a few active pilots of new technologies that do real-time word spotting and stress-level assessment. As these products become more sophisticated in their ability to tag and find particular recordings, there will be more ways to data mine recordings. All of these advanced functions require online or nearline storage.
This was first published in April 2006