Not long ago I helped a few people transfer their landline phone number from Charter Spectrum to Google Voice. The general process is straight-forward, but the devil is in the details. Several steps are prone to failure and delays if not done correctly. This post is my notes about the exact steps required.


The process of transferring a phone number from one carrier to another is called “porting”. (For details, see local number portability.) Google Voice only supports porting numbers from some wireless carriers. One way to port a landline to Google Voice is to first port the number to a wireless carrier. The carrier I chose to use is AT&T Prepaid.


Before beginning the porting process, you will need:

  1. An AT&T SIM Card. I used an AT&T Prepaid Activation Kit, but my understanding is that a generic AT&T SIM Card (e.g. from Amazon) or even a previously used AT&T SIM Card (from either prepaid or postpaid service) would work.
  2. Your Charter Spectrum account number and security code along with the full name and billing address exactly as it appears on the account (e.g. from the online or paper statement).
  3. An AT&T-compatible cell phone to use during the porting process.

Porting Process

To port a landline from Charter Spectrum to Google Voice, use the following steps:

  1. Insert the AT&T SIM Card into the AT&T-compatible cell phone.
  2. Activate an AT&T prepaid plan for the SIM Card. This can be done by online, or by dialing *123*ZIP Code*Plan Code# from the cell phone, where ZIP Code is your 5-digit ZIP Code and Plan Code is the code for your preferred prepaid plan. (I’d recommend 02 for “$2 Daily Plan” or 17 for “25¢ Per Minute Plan”.)

    Write down the phone number assigned to your plan. Note that the last 4 digits of the phone number are the AT&T account PIN.

  3. Transfer the landline number to AT&T Prepaid
  4. Call 611 from the AT&T phone (or 1-800-901-9878 from any phone). Navigate to “more options”, then “tech support” in the current phone tree to speak to a tech support representative. Request to “port a number from a different carrier to AT&T” and answer the questions they ask.

    Be sure to specify the name and address on the Charter Spectrum account exactly as it appears on the account. If the information in the port request does not match the information in Charter Spectrum’s system exactly, the port request may be rejected, which will delay the process.

  5. If the port doesn’t complete immediately, ask for the estimated completion date, then check or call the AT&T Ports Department at 1-888-898-7685 to check the port status.

    If the port is rejected or doesn’t complete by the date given, call AT&T Ports Department at 1-888-898-7685 to inquire and/or retry. If the support rep. is unable to determine the reason the port failed, call the Charter Spectrum ports department at 1-844-881-2092 to have them determine the reason.

    Note that Charter Spectrum contracts with Syniverse for landline porting. If the Charter support rep. is not able to unable to explain the failure, they can call Syniverse to inquire. (Customers are not allowed to call them directly.)

  6. Once the port is completed (“Confirmed” on you may need to “activate service” by confirming a phone plan and funding the account. This will be done automatically by the support rep. if the port completes during the call or can be done by calling AT&T customer support and requesting to “activate service on a ported number”.

    Note that it may be possible to decline service activation (e.g. by deferring “until later”) and save a few dollars. However, I have not tried it.

  7. While on the phone with AT&T support (or in a subsequent call), request the account number. (If there is confusion between the account number and the phone number, specify “the account number for porting to a different carrier”.) It will be a 12-digit number and is not currently available on myAT&T Prepaid.
  8. Sign in to myAT&T Prepaid and copy the name and address on the account exactly as it appears.
  9. Port or transfer your personal number to Google Voice using the information from the AT&T account copied from myAT&T Prepaid in the previous step and the account number provided by tech support.

Total Costs

  • $0-10 AT&T SIM Card
  • $0-10 AT&T Prepaid Plan (It may be possible to avoid “activating service” on AT&T. I have not tried it. Whether a minimum amount is required to fund the account differed. It may be $2 or $10.)
  • $20 Google Voice Porting Fee
  • Lots of time on the phone with AT&T (and possibly Charter Spectrum).