The value of tmnxMobPdnApnAuthAcctSupImsi specifies to remove the
3GPP-IMSI attribute when sending an authentication or accounting
message.
When the value of tmnxMobPdnApnAuthAcctSupImsi is not specifed,
the 3GPP-IMSI attribute shall be sent.
This object was made obsolete in the 3.0R5 release.