Saw different threads on StackOverflow, none helped. At the end, I had to remove the plugin, which I had installed with:

cordova plugin add cordova plugin add cordova-phonegap-estimotebeacons

So, remove:

cordova plugin remove cordova plugin add cordova-phonegap-estimotebeacons

Instead, pull from github:

cordova plugin add cordova plugin add https://github.com/evothings/phonegap-estimotebeacons.git

** BUILD FAILED **

The following build commands failed: CompileC build/HelloCordova.build/Debug-iphonesimulator/HelloCordova.build/Objects-normal/i386/EstimoteBeacons.o HelloCordova/Plugins/cordova-plugin-estimote/EstimoteBeacons.m normal i386 objective-c com.apple.compilers.llvm.clang.1_0.compiler (1 failure) ERROR building one of the platforms: Error code 65 for command: xcodebuild with args: -xcconfig,/Users/goliatone/Development/NODEJS/hyperlocal/hyperlocal-visor/platforms/ios/cordova/build-debug.xcconfig,-project,HelloCordova.xcodeproj,ARCHS=i386,-target,HelloCordova,-configuration,Debug,-sdk,iphonesimulator,build,VALID_ARCHS=i386,CONFIGURATION_BUILD_DIR=/Users/goliatone/Development/NODEJS/hyperlocal/hyperlocal-visor/platforms/ios/build/emulator,SHARED_PRECOMPS_DIR=/Users/goliatone/Development/NODEJS/hyperlocal/hyperlocal-visor/platforms/ios/build/sharedpch You may not have the required environment or OS to build this project Error: Error code 65 for command: xcodebuild with args: -xcconfig,/Users/goliatone/Development/NODEJS/hyperlocal/hyperlocal-visor/platforms/ios/cordova/build-debug.xcconfig,-project,HelloCordova.xcodeproj,ARCHS=i386,-target,HelloCordova,-configuration,Debug,-sdk,iphonesimulator,build,VALID_ARCHS=i386,CONFIGURATION_BUILD_DIR=/Users/goliatone/Development/NODEJS/hyperlocal/hyperlocal-visor/platforms/ios/build/emulator,SHARED_PRECOMPS_DIR=/Users/goliatone/Development/NODEJS/hyperlocal/hyperlocal-visor/platforms/ios/build/sharedpch