The phone call claim is part of why I lean a little towards believing Smollett (I'm at about 60/40).
Clearly if a claim of a phone call is made phone records will be investigated and I find it unlikely but not impossible that two people would put their credibility and future prospects on the line for such an easily discoverable lie with no clear upside.
If there conclusively was no call I'd be fairly convinced the attack claim was a lie.
But here's what I think is more likely to happen. There will be a few events that allow for some ambiguity and further bickering.
1) We might get some anonymous source posting on social media that the police found no such call.
2) We may get confirmation of a call but detractors will stretch the available evidence and the meanings of words beyond reasonable interpretation to claim that the call doesn't fit the proper time window.
3) If they really can't argue about the existence of the call, they'll say it proves nothing and was probably Smollett and his manager planning the hoax. Even though they've been talking about the call logs as missing evidence this whole time they'll persist in saying "no evidence" if the logs turn up.
4) The police may find the logs but not make them public, which detractors will take as evidence that no call exists and police are corruptly protecting Smollett.
5) More anonymous tweets etc. will be trotted out as evidence about the case.