It occurs to me that instead of integrating bit.ly, y'all could just make form letter hyperlinks able to use special merge fields like [Client Online Portal Direct Session URL] that could be set as the Link to. By making the Linked Text something short like "here" as in "click here" it would even be shorter than a bit.ly hyperlink and not need the integration hassle or potential ongoing cost of a bit.ly license. My last SMS link was 171 characters, so I think every time I'm sending a login link I'm getting charged 2x SMS, which is costly at the volume I do.

Update: I realized after posting this would likely require MMS, which isn't supported by S+ so far as I can tell. Here's the HTML that would get it done:

<a href="[Client Online Portal Direct Session URL]">link text</a>