The interface to support this is defined in the following article:
However, there is an additional issue that is not discussed in that article.
By default, the routing callback is only called for recipients that are not defined to the MMSC on the “MMSC Users” page.
In a typical operator MMSC configuration, new MMSC user accounts are automatically provisioned the first time a user sends an MMS message. This configuration is detailed in the article titled NowSMS MMSC Operator Considerations.
A problem scenario develops if a subscriber moves their number from this operator to another operator, after they have already been provisioned on the MMSC. The MMSC will see the user account and attempt to deliver the MMS message directly, without performing a routing lookup.
To address this scenario, an additional MMSC configuration parameter exists. Under the [MMSC] header or MMSC.INI, add the parameter ForceRoutingCallback=Yes. This setting will cause the routing lookup to always occur.
Prior to the 2009-06-30 release, to address this issue, we recommended instead using the setting DisableMMSDirectDelivery=Yes, a setting name which sounds contrary to the intended purpose. This other setting was originally added to NowSMS for a different purpose, but it does have the side effect of always forcing the routing callback.
We no longer recommend the use of DisableMMSDirectDelivery=Yes for this purpose, and instead recommend the ForceRoutingCallback=Yes setting. This is because DisableMMSDirectDelivery=Yes has an extra side effect of disabling the automatic version tracking of MMS clients. Because the MMS read receipt format was not introduced until OMA MMS v1.2, this can cause some clients to generate read receipts as regular MMS messages instead of using the read receipt format.
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