[Q] Cannot subscribe to Google Play Music All Access using carrier billing - Android Q&A, Help & Troubleshooting

This is mostly a post about a specific problem with Google Play carrier billing.
Here is the problem:
I want to subscribe to a trial of Google Play Music All Access
I want to use carrier billing (with my Verizon Wireless phone)
When I select "Bill my Verizon Wireless account", I get a red message stating "Error processing your purchase"
Notes:
Carrier billing usually works for me with Verizon Wireless
I am NOT using WiFI while trying to make the purchase
I do not have blocks on messaging or web purchases with Verizon Wireless
Verizon Wireless support cannot find any reason why the purchase would fail
I am well below the $25/mo. cap for Verizon Wireless carrier billing (I've only spent $.99 this month so far)
Step by step:
I turned off WiFi on my android phone (mostly stock rooted Samsung Galaxy Nexus running JB 4.2.2 on VzW).
I plugged my phone into my PC with the USB cable.
USB debugging is on.
I fired up adb shell on my PC.
I used su to start a superuser shell in adb
I typed:
Code:
logcat | grep --color=auto -i -E 'play|market|store|carrier|billing|finsky|phonesky|vending'
I launched Play Music (version v5.0.1041J.689753)
I opened the menu (...)
I selected "Settings" from the menu
I selected "Try All Access for free" in settings
I was sent to a "Google play" screen titled "Try Google Play Music All Access"
I selected "Try it FREE"
A modal dialog box opened titled "Google Play Music All Access"
From logcat:
Code:
I/ActivityManager( 378): START u0 {act=com.android.vending.billing.PURCHASE cat=[android.intent.category.DEFAULT] pkg=com.android.vending cmp=com.android.vending/com.google.android.finsky.billing.lightpurchase.LightPurchaseFlowActivity (has extras)} from pid 8403
D/Finsky ( 1708): [1] SelfUpdateScheduler.checkForSelfUpdate: Skipping DFE self-update. Local Version [80210006] >= Server Version [-1]
I/ActivityManager( 378): Displayed com.android.vending/com.google.android.finsky.billing.lightpurchase.LightPurchaseFlowActivity: +121ms
I/ActivityManager( 378): START u0 {cmp=com.android.vending/com.google.android.finsky.billing.lightpurchase.PurchaseActivity (has extras)} from pid 1708
D/PlayEventLogger( 1708): ActiveExperiments changed, sending with next LogEvent
D/Finsky ( 1708): [1] CarrierParamsAction.createCarrierBillingParameters: Carrier billing config is null. Device is not targeted for DCB 2.
E/Finsky ( 1708): [186] FileBasedKeyValueStore.delete: Attempt to delete 'params...' failed!
I/ActivityManager( 378): Displayed com.android.vending/com.google.android.finsky.billing.lightpurchase.PurchaseActivity: +153ms
I/qtaguid ( 1708): Failed write_ctrl(u 41) res=-1 errno=22
I/qtaguid ( 1708): Untagging socket 41 failed errno=-22
W/NetworkManagementSocketTagger( 1708): untagSocket(41) failed with errno -22
I clicked "Free"
I clicked "Payment options"
I clicked "Bill my Verizon Wireless account"
From logcat:
Code:
I/ActivityManager( 378): START u0 {cmp=com.android.vending/com.google.android.finsky.billing.lightpurchase.billingprofile.BillingProfileActivity (has extras)} from pid 1708
D/Finsky ( 1708): [1] SelfUpdateScheduler.checkForSelfUpdate: Skipping DFE self-update. Local Version [80210006] >= Server Version [-1]
I/ActivityManager( 378): Displayed com.android.vending/com.google.android.finsky.billing.lightpurchase.billingprofile.BillingProfileActivity: +140ms
D/PlayEventLogger( 1708): ActiveExperiments changed, sending with next LogEvent
D/Finsky ( 1708): [1] CarrierParamsAction.createCarrierBillingParameters: Carrier billing config is null. Device is not targeted for DCB 2.
E/Finsky ( 1708): [186] FileBasedKeyValueStore.delete: Attempt to delete 'params...' failed!
I/qtaguid ( 1708): Failed write_ctrl(u 41) res=-1 errno=22
I/qtaguid ( 1708): Untagging socket 41 failed errno=-22
W/NetworkManagementSocketTagger( 1708): untagSocket(41) failed with errno -22
I/qtaguid ( 1708): Failed write_ctrl(u 41) res=-1 errno=22
I/qtaguid ( 1708): Untagging socket 41 failed errno=-22
W/NetworkManagementSocketTagger( 1708): untagSocket(41) failed with errno -22
D/Volley ( 1708): [155] BasicNetwork.logSlowRequests: HTTP response for request=<[ ] https://android.clients.google.com/fdfe/preparePurchase 0xe8d195d1 NORMAL 133> [lifetime=14351], [size=7526], [rc=200], [retryCount=0]
D/Volley ( 1708): [1] Request.finish: 14363 ms: [ ] https://android.clients.google.com/fdfe/preparePurchase 0xe8d195d1 NORMAL 133
I get "Error processing your purchase." in red print
This line really got my attention:
D/Finsky ( 1708): [1] CarrierParamsAction.createCarrierBillingParameters: Carrier billing config is null. Device is not targeted for DCB 2.
I'm assuming "DCB" is "Direct Carrier Billing", and "DCB 2" might be something like a monthly subscription billed with carrier billing. I make purchases with carrier billling so I'm not sure why it would say "Carrier billing config is null."
To make sure carrier billing is working (still), I launched "Angry Bird Seasons", and went "shopping" for 80 power-up bundles for $4.99. I select the same options for "Payment Options" and "Bill my Verizon Wireless account" and "Buy" (bringing me to the "Confirm password" screen, where I canceled the purchase).
This line stood out from logcat:
Code:
D/Finsky ( 1708): [1] PurchaseFragment.runCompleteFlowAndContinue: Start complete flow for DCB3 instrument.
"DCB3" ???. Maybe another "Direct Carrier Billing" purchase type (for a one-time consumable purchase)?
Since Google Play is not open source, I have no way of looking at the code to see what these debug lines actually mean.
Can anybody give me any guidance on this?

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Having the same problem with a rooted Droid RAZR. Does it on both the stock rom and CM10.1.
Edit: Called customer service. They are looking into it. Told me they should contact me back in 24/48 hours.