10-10-2011, 12:35 AM
| | Re: Cingular? or AT&T?
In article <firstname.lastname@example.org>,
tlvp <mPiOsUcB.EtLlLvEp@att.net> wrote:
>A GSM phone I keep on standby here at home, with a Polish SIM in it,
>generally roams onto an AT&T tower, and its face declares:
>| Orange |
>| AT&T |
>Occasionally, though its face declares instead:
>| Orange |
>| Cingular |
>Any conjectural explanations? (Fwiw, the SIM is from Orange (PL),
>while the handset is a SIM-unlocked, Cingular-branded, LG cu-400.)
You phone was probably roaming on different portions of the AT&T network
which had differing carrier ID's. Depending on the age of the SIM and
whether or not the carrier ID is in your SIM card's lookup table, it may
translate to different text equivalents.
Long ago I saved the text below from a newsgroup posting. I'm sorry for
the lack of attribution, I can't find it anymore and don't know who the
author was, but it gives you a flavor of the complexity of this process:
Rules for display:
1. If Mobile Country Code (MCC) and Mobile Network Code (MNC) broadcast on
the network match the MCC and MNC on the SIM, the Service Provider Name (SPN)
on the SIM is displayed.
1.5 If the MCC-MNC combination match one of a set stored in the SIM, the
name associated with that set is displayed. That is why you may see
"AT&T" for other networks (e.g., T-Mobile in Seattle), and "Extended
Area", "Roaming", or "Canada Roam" for other networks.
In this case, the name displayed does not indicate the network name, but
rather the roaming status:
AT&T home network features and pricing, even if roaming
on a non-AT&T network
Extended Area roaming with home network pricing, but not all
Roaming roaming, subject to additional charges
Canada Roam Welcome to the Great White North, eh?
Verizon phones have much the same behavior. Different Verizon PRLs cause
different display when roaming, depending upon what your service plan
offers for roaming.
2. If the MCC-MNC combination does not match, the phone checks a table in its
firmware for an entry corresponding to the MCC and MNC received. If found,
that entry is displayed.
3. If no table entry is found, the country abbreviation (or the MCC if no
country name entry is found in firmware) and the MNC are displayed.
* Public Land Mobile Network (PLMN) name; or
* Mobile Network name (shortened form of the above); or
* Service provider name (SPN) (as stored on the SIM).