Since some of the sorts of services that are expected to use .tel domains can be achieved on mobile telephones, there may be a perceived overlap with the intended use of the .mobi domain, which was also approved by ICANN in the same round.

However .tel is about publishing contact data: phone numbers, SIP addresses and so on directly in the DNS, not on html-based websites, whereas the focus of the .mobi domain is providing web sites and other content formatted specifically for the user interface available on mobile phones and other mobile devices. 

.tel is viewable from both desktop and laptop PCs as well as mobile browsers due to the restriction of the A record, the reason for the proxy pages which are locked by Todayisp.com and which provides the template for all .tel domains to be viewed on the web.