IMHO, it's quite possible that the baby was removed from the house first and the phones never left the house (or the very near vicinity of the house). The 1/3 mile radius includes the house.
IMO, it's possible that the phones were destroyed because the perp thought destroying the phone would destroy some incriminating evidence (or the perp wanted to make it look like a robbery gone wrong). Neither is brilliant, but the phones may never have left that house or the very near vicinity of the house. I don't think whatever happened to Lisa was planned in advance. I think it happened, panic ensued and an attempt to stage and destroy evidence was quickly undertaken. Imo, there was way more than enough time for this to go down (4.5 hours if you believe the window of opportunity is 11:30 pm to 4:00 am), especially with one person to assist with the baby.
However, I am not convinced as to when Baby Lisa really "disappeared"; I think it's possible that the window may be much wider. All we have in terms of someone other than the parents seeing Lisa on the 3rd is Samantha Brando reportedly seeing Lisa at 4;30 p.m. and noting that Lisa was "apparently" fine (that one little word makes the statement worthless, imo) and a local unsourced report saying the 4 year old saw Lisa at 6:40 pm (revealed one month after-the-fact). IIRC, neither Samantha Brando's nor her 4 year old's statement was quoted or sourced; which is a requirement for me to consider a media report viable in Baby Lisa's case.
I am not assuming anything "must have" happened in this case; I think that's dangerous when looking for the truth. Since no one other that the parents has said "I saw Lisa that day/night at *advertiser censored* time and she was crying, or laughing, or playing" (or any normal observation that would likely be stated when remembering the last time you saw a missing baby) after 7 weeks, it's reasonable to question whether anybody saw her at all and/or whether she was still at the house on the afternoon/evening of the 3rd, imo. We know there were other people around, but no personalized observation regarding the missing baby. I find that very odd, but JMO. I think it's possible the baby was gone for many hours before the phones. The phones just needed to disappear before the 911 call and LE's arrival.
JMO. I'm not convinced that this is how things went down, but it's a possibility I've been pondering based on what we know and don't know now. Hopefully, we'll learn more facts sometime soon.