Mobile electronic communications with grace period

1. A method at a server of controlling voice calls and messages, the method comprising:

maintaining an indication of a balance in a balance data record of an account associated with a mobile communications device, the indication of the balance being adjusted to indicate a reduction in balance in response to at least one of establishment of a voice call over a mobile network or sending of a message over the mobile network;

tracking a grace period using a grace-period data record while the balance is depleted, the grace period having a predetermined duration that begins from a time that the balance is determined to be depleted;

if the balance is sufficient to place the voice call or send the message over the mobile network, allowing the mobile communications device to establish voice calls or send messages over under normal operating conditions; and

if the balance is insufficient to place the voice call or send the message over the mobile network, during the grace period:

disallowing access by the mobile communications device to the mobile network; and

allowing the mobile communications device to establish voice calls or send messages over an available wireless local-area network.

2. The method of claim 1 , further comprising expiring the grace period, and disallowing the mobile communications device from establishing voice calls or sending messages over the available wireless local-area network outside of the grace period.

3. The method of claim 1 , further comprising sending an indication of the grace period to the mobile communications device.

4. The method of claim 1 , further comprising, during the grace period, sending unrequested content to the mobile communications device for output at the mobile communications device.

5. The method of claim 4 , wherein the unrequested content comprises advertisements.

6. The method of claim 1 , wherein allowing the mobile communications device to establish voice calls over the available wireless local-area network comprises allowing the mobile communications device to establish voice over Internet protocol (VoIP) calls with a VoIP service over the available wireless local-area network.

7. The method of claim 6 , comprising tracking the balance data record and the grace-period data record at a server distinct from the VoIP service.

8. The method of claim 1 , further comprising receiving a payment for the account associated with the mobile communications device, and, in response to receiving the payment, clearing the grace-period data record.

9. A communications system comprising a server, the server configured to:

maintain an indication of a balance in a balance data record of an account associated with a mobile communications device, the indication of the balance being adjusted to indicate a reduction in balance in response to at least one of establishment of a voice call over a mobile network or sending of a message over the mobile network;

track a grace period using a grace-period data record while the balance is depleted, the grace period having a predetermined duration that begins from a time that the balance is determined to be depleted;

if the balance is sufficient to place the voice call or send the message over the mobile network, allow the mobile communications device to establish voice calls or send messages over under normal operating conditions; and

if the balance is insufficient to place the voice call or send the message over the mobile network, during the grace period:

disallow access by the mobile communications device to the mobile network; and

allow the mobile communications device to establish voice calls or send messages over an available wireless local-area network.

10. The system of claim 9 , wherein the server is further configured to expire the grace period, and disallow the mobile communications device from establishing voice calls or sending messages over the available wireless local-area network outside of the grace period.

11. The system of claim 9 , wherein the server is further configured to send an indication of the grace period to the mobile communications device.

12. The system of claim 9 , wherein the server is further configured to, during the grace period, send unrequested content to the mobile communications device for output at the mobile communications device.

13. The system of claim 12 , wherein the unrequested content comprises advertisements.

14. The system of claim 9 , wherein the server is further configured to allow the mobile communications device to establish voice over Internet protocol (VoIP) calls with a VoIP service over the available wireless local-area network.

15. The system of claim 14 , wherein the server is further configured to track the balance data record and the grace-period data record at a server distinct from the VoIP service.

16. The system of claim 9 , wherein the server is further configured to receive a payment for the account associated with the mobile communications device, and, in response to receiving the payment, clear the grace-period data record.