What do I mean by this?
Simply that too many sales professionals have a single product or service focus. They think and act sequentially - in a series of singular steps.
If we are committed to 'service' being the root of selling then we should consider developing more holistic attitudes to our clients. Who else is involved in the business and needs to know that I'm servicing the business with an existing solution but can provide others? Have I had my existing contact draw a map or flowchart of the firm indicating where everyone is and who other potential decision-makers might be?
What am I doing about working as an advocate for my client - a true business partner? When did I last refer business to him/her? When did I last do something that made them look good in the eyes of their company or clients?
Am I the 'networking point' for their business needs? Just because I can't provide the solution shouldn't mean that I don't maintain a database of other (non-competing and quality-focused) service providers and then I suddenly become the peson who always gets the first phone call when there's a need - because I have become the '(wo)man who can' for their business.
Think about it. Sell holistically and add more value to your (and their) bottom-line.