Salespeople will never cold call. Stop trying to make them.
Cold calling is an inhuman thing. It is rife with refection and hard as hell. It is also an inefficient activity that your reps will never want to do — especially highly-trained outside salespeople. This is because they do not know how to go about it. They were probably never trained for it. They are also not incentivized for it; most salespeople are not compensated for prospecting directly, and they would rather focus on things like reselling clients. And newsflash, they are not good at it either. Prospecting requires a unique skill set and state of mind, and ultimately, a different person doing the task.
Yet, making the first contact with the market is extremely important and necessary. It is the very nexus between sales and marketing, and the start of the entire sales process. The only way to get it done is to decouple this activity from outside sales; it should be done at different times in different locations by different people. You must train, manage, and pay for it specifically. It also requires its own feedback systems and performance measures.
This intermediate step in the sales cycle must be treated as an end goal in itself for your inside reps — as opposed to just a pain in the butt along the way for your outside reps. And let’s face it — they will never do it anyway.