In Season 3, Episode 8, Convivir, Miguel captured Enrique who ratted out Jorge as the American informant, but during the final confrontation, the skypager given by the DEA to Jorge somehow ended up in Enrique's pocket.
How did it happen?
Notice that Jorge walks up to Enrique, grabs hold of him, and tries to get Enrique to admit he's lying. It is only after this has happened, that the SkyPager is discovered in Enrique's pocket.
Just before this scene took place, we saw Jorge hold the SkyPager (deleting some messages), which proves that he hadn't just slipped it into Enrique's pocket before Enrique was captured (e.g. at the safehouse).
It also doesn't make sense for Jorge to have done this at an earlier stage. The last time he saw Enrique was in the safehouse, and slipping the SkyPager into his pocket then would have been an incredibly stupid thing to do. He wasn't expecting Enrique to get captured (he was only found after he called his brother, Jorge specifically told Enrique to not call anyone) and if Enrique had found the SkyPager while in the safehouse, he would've suspected Jorge to be the mole and would've called David or Miguel.
Therefore, the only logical explanation is that Jorge slipped the SkyPager in Enrique's pocket when he approached Enrique to confront him about his (supposed) lies.
In the nick of time, Salcedo manages to slip the skypager, an american technology, in Enrique’s pocket and gives everyone the smoking gun they need to kill him and close the case.
It was clearly shown in a previous scene that Jorge was using his SkyPager. So this means he had it on him when he confronted Enrique and David.
It was when Jorge grabbed Enrique to get the truth out of him, he slipped the pager in his pocket. That could only be the logical explanation as to why the SkyPager ended up in Enrique's pocket.