I just recently got Nextel service and had 2 incidents where VM
notification was 12 and 36 hours late.

It was explained to me (by an engineer, not a CSR) that if you have no
signal for more than 2 or 3 hours, the SMS notifications get sent to a
different queue and could take a long time for delivery.

I really like the service so far but I get out of range quite a bit
and this does not seem like a very clever implementation of SMS to me.

See More: Voicemail notification delay