and use them based on their rates (different destinations, time of day, and SO on), you can do it without any fixed overhead. But, the major disadvantage is that you might not get good rates from the service providers. Bundled Offer Some SIP providers sell SIP trunking at $20 per month per trunk, which comes with one phone number. They can reduce the rate to as low as $10 per month with a 3-year plan. Additional phone numbers are sold in packs of 10, 20, or 100, ranging from $7.50 per month to $50 per month. So, if a company wants to enable five concurrent calling lines 52 SIP Trunking to be spread across 15 people, you can take five trunks and a pack of 10 additional num- bers. Some service providers offer per-minute plans and a 1500-minute plan for $39.95 per month. When you buy bulk, the price might go down to $10 per month bundled with 2500 minutes per month, and you pay between 5 and 10 cents per minute based on your volume. You will not get a volume discount for a distributed solution. This is one of the major reasons to go for centralized or hybrid deployment solutions. In some cases, a metered approach fits better with a customer's accounting system, but you might get a better deal with a bundled offer. We analyzed a large national retailer that is expected to save 25 percent on its monthly telecommunications and networking costs by using SIP trunks. That retailer has 1130 stores nationally, with approximately 12 local lines per store, resulting in approximately $736,000 in monthly costs for all its stores with traditional TDM technology. By switch- ing to SIP trunks and related upgrades, the retailer cut in half the number of trunks it needed to operate. Burstable Shared Trunks Some service providers enable you to share the trunks among multiple locations. This is a much better way to manage trunking resources because it uses idle trunk capacity in one location to accommodate an increase in traffic from another location. For example, assume you have offices in three different locations and you need T1 (2