Open-source routing vendors don't agree that their products don't match the capabilities provided by proprietary vendors. Dave Roberts, vice president of strategy and marketing at Vyatta, says that the company is in discussions with a number of companies of varying sizes that want to keep costs in check while being able to change source code to meet their needs. Open-source offers this capability, and proprietary systems don't, he says.

But some companies don't have the technical expertise needed to tweak open-source code to meet their own needs, counter Rao and Cisco officials. Universities, which have students and staff with technical expertise, are notable exceptions. And even companies with some technical expertise may not have the necessary open-source knowledge to maintain the systems on their own. American Fiber Solutions, for example, contracted with Asterisk creator Digium Inc. for technical support as well as for the Asterisk system itself.

Bill Miller, vice president of product management and marketing at Digium, admits that most of his company's customers are those with some internal expertise. But he says Digium also provides support for those customers and prospects that need it.

Cisco counters cost claim

Joe Burton, Cisco's director for engineering for unified communications, counters that once the cost of support is factored in, Cisco's system is competitive on price with open-source systems. Additionally, he says, Cisco uses open-source, notably the Apache Web server, in some of its products.