The first 2 calls came at 3:15 and about 3:45 AM and the one this AM at 4:57.  No ID shown on either phone and afraid to block because elderly mother shows as Private Caller or Blocked Caller depending on which phone I check and if some sort of emergency arises I want her to be able to reach me.  We have an agreement that she will leave a very brief message so I know it's her calling and I call right back, but sometimes I stupidly answer without looking, especially in the middle of the night or very early AM. 

sherriem wrote:afraid to block because elderly mother shows as Private Caller or Blocked Caller depending on which phone I check ...  I want her to be able to reach me.  We have an agreement that she will leave a very brief message so I know it's her calling

Saw your post on 800notes, and had a possible answer for you ... but your description here (your mom's calls display the same message as does the spammer's) invalidates what I was going to suggest.

However, if you have a phone answering device, you might use it ... if the spammer leaves NO message, but your mom does leave a message, that would be a helpful tool.   Set the volume rather high on the answering device, so it might awaken you if necessary.

Unfortunately, if the spammer leaves a message ... my second suggestion will also be invalidated.

Thanks for the hints.  Voicemail clicks over after several rings but so far the only message has been essentially dead air so I know it isn't her.  Still it's disturbing at 3 AM and 4:45 AM.