Network Vision is an infrastructure that allows Sprint to run multiple network technologies and host multiple spectrum bands at the same set of sites. As it's deployed, Sprint is installing LTE as well as upgrading its 3G CDMA system, while the narrowband iDEN network originally used by Nextel. Sprint had said it expected the Network Vision deployment to reach 12,000 cell sites this year.

"While we're encouraged by the momentum of the project, we have been seeing some delays from our vendors, largely related to logistics execution and material shortages as well as some delays related to the hurricanes in the third quarter. And now, we believe, we're approximately one quarter behind in hitting the 12,000 target," said Steven Elfman, president of network operations and wholesale, on a conference call with financial analysts.

However, he said the delay "has not meaningfully delayed" Sprint's forecast for the overall project's timing or cost. Sprint expects Network Vision to be largely complete by the end of next year.

Sprint lags behind the two largest U.S. operators, Verizon Wireless and AT&T, in LTE deployment. It offers LTE in 32 cities, while Verizon has it in more than 400 cities and AT&T expects to reach 100 cities by the end of this year. On the call, CEO Dan Hesse acknowledged a disadvantage on LTE availability versus bigger rivals but said: "Our network position, we believe, is temporary and we plan to catch up." Sprint said recently it would roll out LTE in 115 more markets in the coming months, without being more specific.

The planned in Sprint by Japan's Softbank, announced earlier this month and still awaiting shareholder and regulatory approval, should help the carrier gain the scale to better compete, Hesse said. He said Sprint's smaller scale caused it to be late to LTE and to offering Apple's iPhone and iPad.