Blackberry (BB) released dual mode handset. This handset can be used in GSM/3G or in CDMA network.
Based on my experience, even tough BB has been attached to GSM/3G Network, it seems BB still trying to use CDMA APN at the first time. If the APN rejected (due to operator’s APN differences), then BB will try to PDP using the GSM/3G APN.
This behavior will make a little problem if provider trying to implement APN Redirection
The aim of applying APN redirection for BB subscriber is to handle wrong APN requested by subscriber.
In the simple way, SGSN will redirect all non providers APN requested by subsciber to blackberry.net if and only if the subscriber is a blackberry subscriber
So, if the subscriber uses other APN eg emgsm.vzw3g.com, celcom, vodafone, etc, SGSN will redirect the APN to blackberry.net as long as they’re blackberry subsciber.
Technically, the APN parameter value on Active PDP Context Request Is emgsm.vzw3g.com, but the APN parameter value on PDP Context Creation send by SGSN to GGSN is blackberry.net.
Since the subscriber eligible to use APN blackberry.net (subscribed in HLR), then GGSN will allow this subsciber and give PDP IP to the subsciber
The BB device will only send packet to the RIM IP.
Because BB handset “feel” that the PDP Activation was successful using CDMA APN then BB will send the payload traffic to RIM CDMA IP instead of RIM GSM IP.
RIM will reject the packet because RIM only open the packet for GSM IP. This is what I called problem.