I recommend a chat service for your website (instead) as the virtual chat agents are likely to get more information from your customers. For a telephone service maybe just use a selection service so the customer can choose the department they want to go :)
Check out Tawk.to - their chat is free and you can use it on your mobile - but they also have a virtual chat agent for $1 per hour (USD) https://www.tawk.to/hire-chat-agents-1hr/
I use Tawk.to for all my clients websites who want a chat service, it's perfect & free!