some usefull info for gsm users posted by skreelink on xda:
GSM USER INFORMATION
It seems there is a lot of confusion about using the rom on GSM networks... false information about requiring build.props, flashing radios, etc. so I will give some general information...
EITHER METHOD; THE PHONE MUST BE UNLOCKED WITH EITHER AN UNLOCK CODE FROM VERIZON OR BOUGHT FROM A 3RD PARTY SOURCE.
FOR DROID 3 XT862 ONLY, XT860 REQUIRES A PATCH FOR RADIO DRIVERS.
USING NON-US "FOREIGN" GSM NETWORKS
Stock XT862 radio
Default included build.prop (Edit lines ro.mot.phonemode.vzwglobalphone=1 and ro.telephony.default_network=7 IF REQUIRED to ro.mot.phonemode.vzwglobalphone=0 and ro.telephony.default_network=3 respectively. )
MAY NOT BE REQUIRED TO EDIT THESE LINES
Under Wireless & Networks section; UNCHECK Enable alt OEM and Enable Alternate getIMSI, then CHECK Enable World Phone and Enable GSM Signal.
Reboot the phone.
Back in the menu; select mobile network settings, change Network Mode to GSM/WCDMA, check/add/edit your APNs.
NO FLASHING/MODIFIED BUILD.PROP REQUIRED (except mentioned build.prop edits which are NOT required, just cosmetic, might not be needed)
USING US GSM NETWORKS (AT&T, T-MOBILE, Etc)
XT883 radio (Baseband n_34.18.16s)
Edited build.prop attached to this post. (No editing required, remove .zip from the end)
Same as above.
Follow instructions on flashing the radio here; http://forum.xda-developers.com/show....php?t=1406812
Use the radio img I uploaded here; http://www31.zippyshare.com/v/98608047/file.html (It's newer than provided in previous link)
Copy the attached build.prop (make sure to backup original) to /system and set permissions rw-r--r-- (644) remove .zip (it is not an actual zip)
MUST FLASH XT883 RADIO AND COPY BUILD.PROP, ELSE NO SIGNAL, PHONE NUMBER, BASEBAND, ETC.
Personally I use a Droid 3 XT862 on Straight Talk's SIM BYOP plan with an AT&T version SIM, I get HSPA 14.4 network and average ~5 to 5.50Mbps download speed. Only issues are known issues with the phone, everything radio related works flawless.
MMS ON GSM WORKS.
Just remember to include "mms" in the APN type, or as required by your carrier.
Just for information; If your data seems unstable, you can try my ril lines in build.prop that seems to have stabilized my data (Tested on MavROM on Straight Talk) these are ALREADY INCLUDED on the attached build.prop.
The main line here is "ro.ril.hep=0" all other lines are not required and may be placebo. This line seems to be key for making 3g stable, especially data roaming.
DOWNLOAD BUILD PROP: