The other day, I was driving on I-5 in far northern California,
returning from Oregon to San Francisco. My cellphone is a Samsung
SCH-3500 on Sprint PCS, and Sprint has a major gap in coverage between
Ashland OR and Redding CA. Since I was expecting an important incoming
call, I put the phone into "Automatic" roaming mode, which can roam on
analog or digital networks. There was a stretch around Dunsmuir where
I couldn't even get a signal on any compatible roaming network, but
then I picked up an analog signal and locked onto it.
The part that got me wondering the most, though, was when I got into
Redding. I was into the city of Redding itself, which has good
coverage on the Sprint PCS network. However, the phone stayed locked
onto the analog roaming signal, even though there was no inbound or
outbound activity. I finally had to switch the phone back to
Sprint-only mode to get it to re-test for a signal; it then promptly
latched onto a solid signal and registered with the system, picking up
a voicemail that had been left earlier when I was off the air.
So my question is, if a cellphone is in standby mode and has locked
onto a roaming signal, what is the protocol for trying again to lock
onto the preferred carrier? I would guess that I was in roaming mode
in Sprint coverage territory for at least about 10 minutes without
ever detecting that I could and should switch back to the Sprint
I could understand that the phone would stick with the analog roaming
carrier if I had a call in progress, but it seems like it should be a
bit more diligent about detecting that it no longer needs to roam.