Telecom Engineer

A simple google search gave me this in about 1 minute:

https://www.shockwatch.com.au/product-category/impact-tilt/tilt-indicators/

Knowing where to find information is almost as good as knowing it.

What you know is limited, what you can learn is not...so better

I think you need an instrumentation engineer and not a telecom engineer. (Yes, many telecom engineers can also act as instrumentation engineers but it is a different discipline.) I would use a MEMS inclinometer sensor module, like this company's product, combined with a simple single board computer or microprocessor to insert the tilt data into the available telecom stream. A PLC system may also be able to handle this communication.

I expect you will have to low pass filter your results to remove momentary trips. It will probably also be a good idea to have a structural engineer at least look at the tower to say if a half degree tilt should be considered normal or not.

High accuracy measurement of deflections of an electricity transmission line tower

https://www.sciencedirect.com/science/article/abs/pii/S0141029614005434

If it were not a homebrew tower then a call to the tower's original manufacturers would be a good place to start, always assuming that the tower is sufficiently functional to be able to handle the call.

If you are referring to the actual positioning of the tower, I would think hanging plumb bob on a wire would allow you to check for movement in the tower.

Or have a survey crew check its plumbness twice a year and after sesmic and severe wind events.

If you are refering something truly telecom, I am sorry I wasted your time.

There are several listed on a well-known internet auction site (name withheld) right now, starting from £0.99GBP.