Options on upgrading equipment

The way old phone wires are twisted and designed, are not the same how UTP is twisted. You can very well try, but I'm about 99.99% sure you will fail (since video data isn't just a few packets, it needs a STABLE connection). Scrap that, I didn't take the distance into account. It's about 99.99999999% sure of failure.
You will either need fiber or long range wifi (Ubiquity), but of course, if you have no weather resistant station or box to place electronics in (including electricity), you're left with no options.

It's not going to work

1. Max distance without repeater is 300 fit
2. It must be Cat 5 or Cat 6 twisted

It loks like airFiber 24 is your perfect solution

Please read specs.
https://www.ubnt.com/airfiber/airfiber24/

or build a wireless bridge ussing
airMAX®2x2 PtP Bridge Dish Antenna

https://www.ubnt.com/airmax/rocketdish-lw/

Is the wire inside a conduit? Any possible way you could use it as a pull string for a new cat6?

CAT6 is not rated for 1800 feet

How about a DSL extender? No new wire required.... unless it's bad.

https://www.amazon.com/StarTech-com-VDSL2-Ethernet-Extender-Single/dp/B002CLKFTG

I really appreciate the information and attention given my question. as the answers came in other issues presented.. I do not have direct line of site for more high powered wireless solution was less likely to be effective. the wire in the ground has great connectivity and tones out well.. I am waiting on the VDSL to arrive and see if it will work..   so this is not resolved but under continued R&D and deployment. Thanks to all respondants