First about your specific question: both oír and escuchar are correct. However, No te puedo oír bien does not sound natural. Most people would rather say simply No te oigo bien. Spanish poder is not used as liberally as English can.
Oír and escuchar are synonyms. Though escuchar implies intent (a deliberate action) and oír suggests passive hearing, in practice, in many cases and according to dialect, personal preference and such, both verbs are used interchangeably.
I'm translating here something from Fundeu (a foundation that responds to questions about Spanish grammar and lexicon):
Q. My query is about the distinction between the verbs oír and escuchar. The former does not imply intent, but I wanted to know whether using one instead of the other is necessarily a lexical mistake. In English the distinction between listen and hear is very strict, but lately I have the impression that the rule in Spanish is being relaxed.
A. No, it is not a mistake. In fact, in Latin both concepts were already confused and in Spanish this comes from long ago, as with derived words and phrases like oyente, derecho a ser oído, audiencia… The [Real Academia Española], although it also marks this distinction, admits that the mix of meanings comes from antiquity and does not consider it incorrect.
As I said above, both verbs are used interchangeably, but it often depends on individual or dialectal preference. That is, some people prefer oír over escuchar. According to the DPD, escuchar used in the sense of passive hearing seems to be common in the Spanish of the Americas.