Assistant for US-based Ad Operations

What the JOB is about: my company specializes in helping advertisers (usually from abroad, like the UK or E.U), advertise in the US. To do so we recruit associates that create account in banks/ incorporate companies here in the US and then the advertiser manages this on their behalf, in exchange they get a monthly fee. What I'm looking for is someone who can manage communications with them (for now it's early stages so It'll be one or two), it will involve asking for documents, giving them directions etc. (Of course all of this will be explained to you aswell). Sometimes it would require to give them a call on their phone (we will provide the number of course). It is a long-term thing, at the start It will only be occasional and require only 1-2 hours of work in a day maximum, but as we grow we might need someone to involve full time. Would you be interested in this?

Note: I need someone that available quite fast in same day notice and responsive, like if our associate needs/asks something he needs to get an answer in the same day, this is very important.