I've never used 'mobile' but did find something at VB.
Can you choose to display it if you 'go advanced'?
How to Auto Enable Signature Checkbox in Quick Reply Mobile Style - vBulletin Community Forum
Yes, it will display if i go to "full site" mode..
I think that's what you meant?
The coding on that VB site, unfortunately, only applies to VB bulletin boards (note the style sheet coding begins with "vb") i did try to paste it in my signature but the way the coding is formatted.. it won't allow for line breaks, giving me a "you have too many lines in your signature" message.
AFAIK.. i don't have access to manipulate the coding associated with the mobile template..
I do really appreciate your help though!
Update.. just realized the forum is a VB bulletin board.. even so.. i do think that it's something that would have to be done server side.