This might not directly answer the question, but I'd challenge your assumption that you need to hide call links on other devices.
Why?
- Non-phone devices can still make calls. For example, a PC with a VoIP client can handle
tel:
links.
- Tablets (iPad and Android) handle
tel:
links by allowing the user to add the number to their contacts, which would undoubtedly be synced to their phone – a nice convenience for your users.
- Relying on automatic format detection is a hack.
So just leave it as a regular link. Maybe make it obvious by linking the phone number, so that someone on a desktop with no telephony software will understand that nothing will happen when they click it.
Call Us Now at <a href="tel:12345555555">(234) 555-5555</a>
Also, remember that a tel:
link won't result in a 404 error since a HTTP request is never generated. On my machine with no tel:
handler, Chrome simply does nothing, IE9 says "Some content or files on this webpage require a program that you don't have installed." (reasonable), and Firefox says "Firefox doesn't know how to open this address, because the protocol (tel) isn't associated with any program." (also reasonable).
When I was faced with this problem, I decided that the benefits of just leaving in tel:
links outweighed any downsides or messy alternatives.