First, when you purchase your coaxial cable, make sure it's 75-ohm because this is the impedance used by TV's (and CATV providers as well). There are a lot of coax cables being sold (specially in Raon) but not necessarily 75-ohm (e.g. 50 ohm RG-58, RG-8, for two-way radios or local area networking, etc). When there is a mismatch between the load (TV) and the transmission line (cable), it results into losses or standing waves, neither of which is good for the quality of your signal.
Second, evaluate the quality of the cable in terms of the shielding or brading (this is the wire covering the insulation of the center conductor). The brading is designed to minimize the interference. The higher the percentage of shielding, the better. If you see the Swan brand, don't purchase that. Try to strip the outermost jacket of the cable and you'll understand why. Belden had always been my trusted cable for over a decade because of their quality, specially in the percentage of shielding. Destiny used to provide decent quality ComSpec RG-6 cables but have now shifted to some cheaper Taiwanese RG-6 cable (probably due to cost-cutting).
Third, decide on the over-all thickness of the cable when you have selected your preferred brand. This is usually designated by the prefix "RG", which stands by the way for Radio Guide (it was supposed to help consumers easily determine one cable size from another but as you can see, it did not meet its objective). The 75-ohm cables are usually RG-59 and RG-6, the latter being stouter and consequently stiffer than the former. If there is a possiblity that you will be subscribing to cable internet in the future, I would suggest you lay out an RG-6 at least. There are also RG-11 cables but those are used for lengths of 2,000 feet to 3,000 feet. I don't suppose you'd have a need for those. In case you do, please note that at that length, you might need repeaters/amplifiers/boosters already.
Fourth, don't settle for those "screw on" type of F-Connectors--those are the type that get broken or loose, specially if you have a thick cable. Cable companies use the "crimp-on" types, whether it be the compression kind or otherwise because they are reliable and have better connection. I agree with KPY555--Amphenols are one of the better brands of connectors out there. If you can find AMP, that's good too.
Fifth, check with the building codes of the Philippines if you are particular about the safety of the cable your laying in-wall. In the U.S., cables have to be rated for them to be legally installed in-wall. Again, Belden has those types of cables (some are called Plenum). At the very least, use a PVC to insulate the cable from rats.
I don't know exactly about the voltage of phone lines but the last time I checked, I got a nasty shock when the phone rang while I was holding the phone wire (things might have changed when our phones became "digital", so to speak). I believe that was at least 110v in the old days.
Avesco/5th Avenue is a dealer of Belden cables. As you may already know, this company is a bit on the high-side when it comes to pricing.
It's a bit long but I hope it has helped you get acquainted with transmission lines (i.e. cables). Good luck!
