What is dial-in conferencing
It is not always possible for meeting participants to have access to the internet at the time of the meeting. If this is the case then you can bring the participant in using a landline phone using the methods below.
Please note: It is not currently possible to dial a mobile phone from within Skype for Business. If the participant needs to use a mobile phone, then (s)he can download the Skype for Business app from Google Play or Apple App Store or alternatively (s)he can dial into the meeting using the details included in their meeting invite (phone number and Conference ID).