A continuous approach of the market is just as important as a few intensive campaigns. Campaigns set the stage but a customer will not buy unless the timing is relevant, usually when contracts finish.
So first of all you need to investigate a few things about potential customers; did (s)he just leave you, is (s)he stuck in a contract with your competitor, if so when is that contract ending, are there any signs of dissatisfaction? If you are in the dark, sales is a wild goose hunt.
The first period after you have been chosen is essential. Are you nursing warm relations? Especially when there are startup problems, attention and help build trust. Trust is the starting point for cross and up-sell, it fosters promotors of your service. Ignoring their issues will cause disloyalty, and renders your customers price sensitive. They will sneak out as soon as the opportunity arises.
The basic machinery
Customer data and a reliable sales funnel are essential for good ‘customer lifecycle management’. They carry the whole machinery.
If for example you want to expand your marketshare of mobile subscriptions, you need to know when customer contracts end. This means data crunching. With these data safely stored in Salesforce, communication and sales can plan their efforts.
Sales fosters contacts, communication generates a bedding of brand recognition and repeats the offer (mails, banners), marketing carves an appealing proposition and provides sales scripting.