PreferenceSpecifiers Title Codecs Type PSGroupSpecifier DefaultValue Key speex_16k_preference Title Speex 16Khz Type PSToggleSwitchSpecifier DefaultValue Key speex_8k_preference Title Speex 8Khz Type PSToggleSwitchSpecifier DefaultValue Key g722_preference Title G722 Type PSToggleSwitchSpecifier DefaultValue Key gsm_8k_preference Title GSM Type PSToggleSwitchSpecifier DefaultValue Key ilbc_preference Title ILBC Type PSToggleSwitchSpecifier DefaultValue Key pcmu_preference Title PCMU Type PSToggleSwitchSpecifier DefaultValue Key pcma_preference Title PCMA Type PSToggleSwitchSpecifier