You must enclose group voicemail numbers in quotes. For example: \'xxxxxxxxxx*2\'
Correct: external_transfer_number = \'4156716000*2\'
Incorrect: external_transfer_number = 4156716000*2
external_transfer_livevox_voicemail should be yes for personal agent voicemail transfers only. For group voicemail transfers and transfer numbers outside of LiveVox, external_transfer_livevox_voicemail should be no.