Rod. My experience is not to use the final note as it seems to scare them off. I use a series of 4 or 5 short, quiet squeaks, then wait a few minutes before repeating. I usually give each location about 20 minutes before moving on. Always scan very carefully with binoculars before moving as one can be present but unseen.
I have found that calling from the rides doesn't work well. My method is to quietly enter the woodland block, creep about 40 yards in, then set up my sticks, with my back against a tree. Face mask and gloves to help hide movement, with rifle on sticks at the ready and wait a few minutes before you start calling. Keep movement to an absolute minimum and don't overdo the calling.
Muntjac will often creep in close and may try to get round behind you to get your wind too.
My ideal location is where light to medium cover is in front for 50 or 60 yards, with heavy cover in the background. Best results come from them leaving the heavy cover and approaching in the lighter cover, where I can spot the movement. Muntjac will seldom completely leave cover when coming to the call.
If you get one barking at you from cover, just give it the odd single squeak in response. Such a 'conversation' may go on for several minutes and you may get the chance of a shot if you can spot it as it barks. If you shoot one, don't move immediately, as there may be others present that you are not aware of. Try calling again, as I have shot more than one on such occasions.
Sometimes it works like a dream, other times they completely ignore me. I have never sorted out why. I think that is the main reason why trying to call them fascinates me so. I have shot a lot of Muntjac that came to the call over the past decades.