Does this exist: Carry analog phone signal between two points over Layer 2

I feel sheepish asking this because there's a simple Layer 1 solution, but trust me, it's complicated.

I have a situation where I need to set up an analog phone in an office where one Cat6A data jack is present. The jack feeds back to my access layer in an IDF, where the building's phone lines reside.

Yes, I know: Add more data runs. That's happening, but this is a construction site with a billion high-pri items on the punch list and I won't get them until after people are occupying the space. (I cannot sub out to another electrician.)

Before I go taking the jack apart to borrow pairs (and undo the contractor's cable certification,) I was wondering if there is such thing as a pair of devices that can connect over layer 2, carry the analog signal over SIP or something and, essentially, present RJ11 on both ends.

A PoE+ desktop switch and SIP phone is also an option, albeit less preferred because reasons.

Please feel free to laugh at my ridiculous predicament and provide any insight you might find helpful.