Based on personal experience, I would have to say that weakest communications link in this country is the postal system, also known as Philpost. Over the past couple months, mail sent to me from the U.S. has arrived either late or not at all. Even priority mail items that finally did reach me were not delivered--based on the Quezon City Post Office date stamp-- for three weeks or more after arriving there.
In an attempt to resolve this issue, I called that office. According to a delivery supervisor with whom I spoke, the problem is a shortage of and turnover of mail carriers in my locale which is a densely populated mixed business and multi-unit condominium area but that they're doing the best they can with their available resources to keep up with delivery demands.
Incidentally, finding the phone number for Philpost was a task in itself because that operation is not a government bureau as such but rather a government owned corporation and so is not listed under Philippine government offices. Instead, it's listed alphabetically under Philippine Postal Corporation in the Metro-Manila DPC "Government and Business Phone Directory". Significantly, there's no customer service number listed under that heading in the phone book or on the Philpost website.
So if you are outside the Philippines and are mailing an important letter, consider sending it via registered mail or through private carriers such as LBC or Fed-Ex. If you can get away without sending the primary document itself, there are of course other recourses for correspondence from, to, and within the Philippines such as telephone, fax, email, and text messaging. For residents of Metro-Manila, to improve the chances of receiving your mail consider renting a post office box. Sending money to the Philippines can be done through such services as Philippine National Bank, Western Union, and various Internet services.
Another problem with the postal service here is internal pilferage which is why much of the mail (possibly including my lost items?) goes missing. Also there are no public mailboxes. The reason for this is that they would be highly vulnerable to theft due to the high crime rate here. So mailing a letter requires a trip to the post office or to malls where there are private companies that accept mail and perform other services for Philpost such as selling stamps.
In short, although it's a separate entity from the government, the postal system's deficiencies reflect the culture of inefficiency of its "parent company" and of the Philippine society as a whole. Unless the national character through some miracle drastically transforms itself, it would probably be futile to expect Philpost to function any better than it does now.