What does a bell with a line through it mean next to it by an sms phone# mean?

[Android Central Question]

There a bell with a line through it symbol next to a phone # on my android phone. It is next to an sms phone#

 

[Scienceguy Labs]

There a bell with a line through it symbol next to a phone # on my android phone. It is next to an sms phone#

Does it mean that you have notifications turned off for that contact??