I let a call slip through and when I rang the number back, I was greeted with a robotic voice prompting me to "hold on while we connect you to someone from our team." There was no introduction or indication of who they might be. I've decided to blacklist them.

Picked up the call and was met with a pre-recorded message.

I received a call on my mobile from this number today. When I answered, there was silence on the other end. I chose not to say anything, but it quickly became evident to me that it was a bothersome call. Upon further investigation, I found that there had been several other calls from the same number before.

They picked up the phone, had a brief chat, and then abruptly ended the call.