just got the tracker and I have the same issue.
I have put my numbers with + as on the manual was saying it wouldn't change anything.
Also, I got the same results, if I send the sms to the tracker I got a reply with the position by sms in return, not if I make a call, but the strange thing is I can see that the counter of SMS is updated if I make a call, so it looks like in theory it has sent a sms, but I haven't received anything.
Has anyone find where the issue is?