Out of the 40 appointments booked, how many appointments actually took place?
Average cold call to meeting booked is 2%, so your 4% is above average, but if meetings aren't being held, the first place to look would be targeting + messaging.
If all 40 booked meetings took place and your close rate is 2.5% then the first place to start would be qualifying and discovery on that first call, because as Tony said, you should be closer to 13 closed with 40 meetings.