stalker... please read very important

So I keep getting a phone call as soon as my husband goes to work. I am stupid and I picked up the phone and they said NOTHING.. just silence. Hung up. Called again. Then my husband got home about 6 hrs later and my husband called that number back.. and boom.. it said the number is no longer in service because it's not a working number.
Soo.. my husband had off yesterday(the day after the phone number called and he tried calling back) and my husband and I heard NOTHING. We didn't think anything of it because that number to our knowledge is not working and we figured was a telemarketer. 
Well.. my husband. Went to work left at 3:45 for there at 4 and I get a call at 4:23... THAT NUMBER THAT WAS NOT TCHNICALLY A NUMBER A FEW DAYS AGO.. it only happens when he's at work.. I'm thinking maybe a stalker. I have 2 young children under 3 I'm pregnant. 
And when I look the number up online I get nothing about a scam but it doesn't release the name.. i don't know what to do.. 
I also texted the number the first time I picked up and didn't say anything. And said "who is this?" And no response. 
Please help me.. I am so scared.