The term 'inside sales' designates a process of remote sales development where there's no personal contact between a prospect and a sales agent. The opposite term is 'outside sales', where soliciting is done door to door, via office visits, at conferences and trade shows.
In most instances, inside sales are coupled with inbound marketing, which acts as a lead generation mechanism for future sales development. Advanced inside sales CRM software, like Bitrix24, supports all inside sales channels - telephony, email, social media, messengers, live chat or website forms - and is capable of automating routine 'inside sales' processes for greater efficiency.
If you are looking for free inside sales CRM with over 20 sales and marketing tools, consider Bitrix24 CRM.