[Desire HD Android Development] Wacco001:
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Preferred Network Types changes the type of frequency the phone searches for.

Android is used on several devices that can gain access to different cell carriers.

For simplicity, there are two main types of cell carriers, GSM and CDMA.

The following popular data communication technology is associated with each cell carrier type:

GSM = GSM(2G), GPRS(2.5G), EDGE(2.75G), UMTS(3G), WCDMA(3G), HSDPA(3.5G/3G+) HSUPA(3.75G) {Cell Carrier examples: AT&T and T-Mobile}

CDMA = CDMA (2/3g) EV-DO(3g) WiMax(3/4g) {Cell Carrier examples: Verizon and Sprint}

HSPA+ Evolved High Speed Packet Access (84 Mbit/s in the downlink and 22 Mbit/s in the uplink)

HSUPA (H) High Speed Uplink Packet Access (Category 6 - 5.76 Mbit/s in the uplink)

HSDPA (H) High Speed Downlink Packet Access (Category 8 - 7.2 / Category 10 - 14,0 Mbit/s in the downlink)

UMTS (3G) Universal Mobile Telecommunications System (384 kbit/s -> max 2 Mbit)

EDGE (E) Enhanced Data Rates for GSM Evolution (384 kbit/s)

GPRS (G) General Packet Radio Service (52 kbit/s)

GSM Global System for Mobile Communications (14.4 kbit/s)

Preferred Network types:

WCDMA preferred - Automatically switches between G/E/3G/H based on the best/strongest signal available and is supported by all providers.

Has high battery usage since it constantly scans the network for the strongest signal to switch.

GSM only - Only uses G/E and never switches to 3G/H. Should have minimal battery usage.

(there is a problem with GSM only on some older networks... so if data is used, you can miss calls, thus GSM auto (PRL) is the safest setting)

WCDMA only - The GSM phone is capable of using only 3G data communication. When the 3G signal is too low you get nothing at all.

Only uses HSDPA and will not switch to G/E/3G even if the HSPDA signal is too low. Use this only if you use your phone in a area with good coverage. Should have moderate battery usage.

GSM auto (PRL) - Automatically switches between G/E/3G/H based on the PRL (Preferred Roaming List) for a provider on your phone.

Not supported by all providers and may not be supported in certain regions. Should have moderate battery usage since it uses a predefined list to switch.

CDMA auto (PRL) - The CDMA phone is capable of using both 2G and 3G data communication and when signal strength is low 2G is favored more.

CDMA only - The CDMA phone is capable of using only 2G data communication. When the 2G signal is too low you get nothing at all.

EvDo only - The CDMA phone is capable of using only 3G data communication. When the 3G signal is too low you get nothing at all.

GSM/CDMA auto (PRL) - Some phones are equipped with both GSM and CDMA capabilities. This setting appears to just have the phone attempt to stay connected to the data communication type that works the best.

Unknown - If none of the above fit or the phone is acting weird as far as connecting to the carrier, you will see your preferred network type is set to this

When using the 'only' options you should still be able to make calls.

GSM auto (PRL) tells your phone to connect using EDGE, and obtain a Preferred Roaming List (PRL) from the tower, and THEN switches to 3G when a data channel is required.

WCDMA preferred has the phone try to find 3G directly. This takes more power until a connection is established.

You can verify this below the "Run Ping Test" button. You will see the Network Type say EDGE, then, after a bit, it will switch to HSPDA.

If your phone is near your computer speakers, you will hear EDGE chatter as it obtains its Preferred Roaming List.

You may periodically hear a lot of EDGE chatter if you have nothing requiring a data channel running, because it might drop to EDGE and stay there for unexplained reasons.

In EDGE only areas it saves a lot of battery by not searching for HSPDA when it does not exist.

Cheers,

NOTE: Changes to your settings might lead to problems with your phone. Please take great precaution before you decide to make any change ... :rolleyes: