After a judge said Friday that it could not add new customers due to a finding that it infringed Verizon Communications patents.

Vonage said it believed it will succeed in its appeal and was trying to work around Verizon (down $0.01 to $37.99, Charts) patents.

It also said it will hold a conference call for investors on Thursday. Its shares were down around 11 percent on Monday.

"The question on everyone's mind is, will this be the beginning of the end for Vonage?" asks telecom industry analyst Jeff Kagan. "Will Vonage be a competitor next year or will they just be a story of a company that was?"

Kagan says Vonage can stay in business serving existing customers but cannot grow. That means it will have to lay off salespeople, cut advertising and adjust other sales and marketing activities, he says.

An inability to grow could translate into a slow death for the company, other analysts say.

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