The first products to use Apple Inc.’s HomeKit software, which controls smart home products using the iPhone as a remote control, are not likely to roll out until this spring, according to new reports. The delay purportedly is due to the company’s guidelines, which specify the hardware and wireless technologies that will work with HomeKit, Re/code reports.

Apple announced HomeKit last June. It says it will work with the iPhone’s Siri digital voice assistant to complete tasks like locking doors, adjusting a thermostat and initiating a laundry drying cycle. It said HomeKit would work with products using competing platforms, but that won’t include Nest Labs’ popular thermostat and fire alarm products, at least not initially. Nest was acquired by Google Inc. last year.

The iPhone manufacturer announced its guidelines for the Made for iPhone (MFi) program in November. Apple’s MFi guidelines require manufacturers to use only Wi-Fi or Bluetooth, and also include a specialized chip for authentication. Nest Labs’ existing products are controlled directly from an iPhone app that communicates with a home’s Wi-Fi network, which runs afoul of Apple’s HomeKit guidelines. Nest told International Business Times it was considering the "possibility" of working with Apple. 

"We have a long, ongoing relationship with Apple. Many of our customers are on iOS and have interest in creating a more thoughtful home," a Nest Labs spokesperson said in an email. "At Nest, we are platform-agnostic so we welcome the possibility of HomeKit working with Nest, in addition to other technologies and features that iOS can bring to customers."

Devices using HomeKit cannot directly communicate using a home’s Wi-Fi. Products not specifically designed to work with Apple’s smart home software are required to connect instead to a HomeKit bridge, an accessory that also requires corresponding products to be MFi-certified. The bridge is required for non-HomeKit accessories to use Siri voice commands on the iPhone and iPad, 9to5Mac reported.

Outside of the home, Apple also will require HomeKit users to own an Apple TV if they want to use Siri to control smart home products. The site says the restriction appears related to home security, as any device with physical access to a home, such as door locks, cannot use the HomeKit bridge to be unlocked.

Apple announced last June a number of partners that would create HomeKit-compatible devices, including iDevices, iHome, Sylvania, Texas Instruments, Honeywell, Haier, Philips, Kwikset, Broadcom and Withings. Nest already has a number of products that work with its line of connected appliances, including Philips, Whirlpool, Kevo, Jawbone and Dropcam.

This story has been updated to include comment from Nest Labs and to change an incorrect reference from Nest to Apple.