We use an answer phone service and it easily covers its costs, i.e
you have a landline phone number advertised on your van you get home listen to your answer phone messages and by the time you call them back the caller has already chosen another company,
you are on the road and a neighbour of the house your doing wants a quote for there windows to be cleaned, the answerphone company take the customers details and emails to your phone instantly
you could simply miss the call, hence lost a custy
average months cost are around £60...make sure you agree with the answerphone service not to send sales calls through as that can double your bill