You say she worked for a big telesales company? I would check out whether it was in a call centre and she was answering inbound calls or, if she was doing outbound calls whether it was 'cold' calling or to a database of current customers where she was trying to upsell them e.g. get a better mobile or move them onto a larger tariff.
Here on Tyneside there are hundreds of people calling themselves tele-sales people but 90% of them are working in call centres, promoting a specific product for a few months working to a fixed, pre-determined script. That's not what you want!
Also remember the database of calls is extremely valuable. 95% of the people called will fob her off and want a callback at a date in the future. That is lucrative info and you need to clarify from day one that it's your info - which is a bit difficult if you are only paying her on actual sales made.
What I would advise is that you use her on a self-employed basis (therefore you must let her choose the hours she works to satisfy HMRC rules) working a fixed number of hours (check via telephone log) and pay her a realistic hourly rate (telesales are normally on around £14k but PAYE which would equate to about £8 / hour s/e ) then a fixed amount per appointment which generates a quote My reasoning for paying by the quote is that she cannot effect whether you win the job. Her measurable job is to get you good appointments not sell them.
I would forget paying ongoing percentages and stuff like that as it ends up too complicated and prone to arguments. Only you can determine the amount per appointment but if you think along the lines (and you will be able to refine the following once you have some experience under your belt) of 1) How much you would be willing to pay if you were buying the work 2) how many jobs you actually win per quote. So, for example, if you win one in four jobs and you have paid her a bonus of £10 per appointment each job you win will have cost you £40 quid plus £8 x however many hours it takes her to make 4 appointments. My quesstimate would be 20 hours. So each job you win would cost you £200. Only you would know if this stacks up financially for you but say she gets an appointment that wins you a £100 a month job. That's £1200 p.a and at an estimated gross profit of say 50%, it will make you £600 quid over the year minus her cost of £200 = £400 but of course in year two you don't have to pay her again.
There's lots of ifs and buts in my suggestions and you will have to substitute your own figures as only you know what the value of the work in your area is like and how good you are at converting enquiries into jobs but my suggestions are based on experience.
If she is a proper outbound cold caller and you don't use her, let me know ;-)
