Cisco Cisco IOS Software Release 12.2(16)B

Prepaid tariff switching enhances the SSG prepaid capability by allowing changes in tariffs during the 
lifetime of a connection, thus providing greater flexibility. This feature applies to volume-based prepaid 
connections where the tariff changes at certain times of the day. 

Typically, a service provider would use prepaid tariff switching because they want to be able to offer 
different tariffs to an end user during the time they are still connected; for example, changing a user to 
a less expensive tariff during off-peak hours.

When the SSG is monitoring the prepaid connection based on volume, at the tariff switching time, the 
SSG can switch to the new charging rate. This feature will not affect any existing prepaid functionality, 
including the idle-timeout feature. 

The SSG is not involved in computing the billing rate changes that occur at tariff switch points. 
Billing rate change computations are performed by the prepaid billing server. 

SSG supports prepaid tariff switching by using dual quota tokens that correspond to the pretariff switch 
time period and posttariff switch time-period. The appropriate token is used by SSG during the period 
in which the service is active.

In order to allow for time-of-day rating changes, the prepaid billing server specifies the tariff change 
time and the tokens for postswitch and preswitch periods in its authorization response to the SSG.

The tariff change time is specified in seconds denoting the number of seconds from the 
authorization time when a tariff switch needs to happen for prepaid billing.

At the point of tariff switch, SSG does a token switch and starts using the second token for its prepaid 
connection monitoring purpose. Re-authorization will happen only when either of these tokens gets 
exhausted and not when a tariff change occurs.

 describes the behavior of SSG in the various events that occur when prepaid tariff switching 

takes place.

An authorization response is received 
containing the dual-quota token tariff 
switch attribute.

Tariff switching is enabled on the SSG for a given prepaid 
connection.

During data forwarding, the quota runs 
out before the tariff switch occurs.

SSG performs a reauthorization in the same way as if there 
was still quota remaining, but no tariff switch attributes are 
included in the reauthorization response.

During data forwarding, the tariff switch 
time elapses after the last authorization.

SSG switches from the current quota token to the next quota 
token. The new token retains the same amount of usage of 
the original token. The new quota token is now used for 
real-time accounting.

During data forwarding, the quota runs 
out after the tariff switch.

SSG will send the quota usage in pre- and posttariff periods 
back to the prepaid server in the authorization response.