By default FCSDK will rely on the echo cancelation provided by the iOS deviceVoice Processing Audio Unit.
Some customers have reported echo in some environments when using external speakers. So CaféX has released an option to enable echo cancelation in software which may provide better performance under certain environmental conditions.
To enable software echo cancelation simple pass ACBUCOptionUseSoftwareEchoCancellation as an option when creating the ACBCU object - for example:
uc = [ACBUC ucWithConfiguration:configuration delegate:self options:ACBUCOptionUseSoftwareEchoCancellation];
Specifying this option replaces the iOS system echo cancellation (provided by the Voice Processing Audio Unit) with a software-based echo cancellation algorithm. Most applications will find the default behaviour to provide the best performance, but this option may be worth experimenting with in case of echo problems.