No dial tone tone

If they are VOIP lines they tend not to give you the ringing. If they are all with one carrier the issue may be on their end. I would ask the people that the issue is with if they are using VOIP or a true land line and what carrier they use then call your cell service provider. Your iPhone may be provisioned differently than your husbands.

What do you mean no dial tone, you never hear a dial tone on a cell phone. Do you mean a ringback tone where it sounds like it's ringing on the other end?

If so, that would be an issue with your carrier, contact them

Yes, it absolutely is the carrier, they provide the ring back tone. It has nothing to do with your phone.

Instead of arguing about it in here,why don't you contact your carrier and ask them.

Is this happening on ALL landlines you are calling or just certain ones?