[DrDeke]

Good evening,

I've had a Blackberry 8320 (Curve) from T-Mobile for a few weeks, and I've noticed some strange behavior on my device that occurs after failed attempts to hand a call off from T-Mobile's GSM network to a UMA/WiFi network. I expect GSM-to-UMA handoffs to "fail" from time to time, in the sense that the call will drop, but the behavior I've been seeing seems like a bug in the Blackberry soft/firmware, and not something that is to be expected.

I'll start a call on the GSM network outdoors, then walk into a building. The buildings I've had this problem in do have GSM coverage, but it is relatively weak. These buildings have strong WiFi coverage so at some point, the phone will decide to hand the call off from the GSM network to the WiFi/UMA network.

Sometimes this handoff works fine, sometimes the call drops, and sometimes, something weird happens. When the weird stuff happens, the call audio stops (I can't hear them, they can't hear me), but the phone does not seem to be aware that the call has dropped. The call timer on the screen continues to count as if the call were still in progress.

Eventually, I'll get tired of this and press the "End" button. Once I do this, the phone returns to the main screen as if the call had ended normally. I will then try to place another call (such as to call the person back), but nothing happens at all when I press the "Send/Talk" button. Literally, nothing happens: The phone does not place the call, and nothing changes on the screen. I can keep trying to call the same number or other numbers, but absolutely nothing happens when I press Send/Talk.

If I wait about five minutes and try to place a call, the phone will immediately say "Call Failed". I can try to place the call time after time, and the phone will say "Call Failed" immediately.

If I wait another few minutes, the phone will start working again as normal.

I have captured segments of the phone's Event Log during these handover-crash events, but I am unable to make a lot of sense of them. I can post some event log snippets if it would be of any help.

I am wondering if anyone else has had this problem, and especially if anyone has any ideas on how to solve it. I would like to bring this to the attention of RIM and/or T-Mobile, but my past experience in such matters suggests that it will not be easy to reach anyone at these companies who might be equipped to investigate or deal with something like this.

Cheers,
Rusty

[John Clark]

Does this happen if you go from EDGE to UMA at a TMobile hotspot like Starbucks?

[DrDeke]

I don't know; I'd have to check. Although I'm gonna look a little strange walking in and out of a Starbucks all day staring at my phone ;).

[John Clark]

Wirelessly posted (BB 11020: BlackBerry8320/4.3.1.27 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/100)

So. I've done it when troubleshooting UMA issues. I don't even drink coffee!!

[DrDeke]

Oh, I'm not saying I'm not gonna do it! I was just sayin', that's all...

However, T-Mobile locations aside, it appears that the problem does not even happen on my own home AP, which is definitely not a T-Mobile hotspot. It's not even a T-Mobile branded router; it's just an Airport Express (Apple 802.11g AP).

I have only experienced this problem in locations with multiple APs on the same VLAN broadcasting the same SSID. I have inter-AP handoff enabled for both of these SSIDs; I'll have to try disabling it and see if that makes a difference...

Another variable could be the fact that my home has very strong T-Mobile GSM coverage, whereas the campuses where I've had this problem have moderate-to-weak GSM coverage... I'll have to test this at a friend's house with a WiFi AP and weak T-Mobile coverage.

[John Clark]

I would say that it's an issue with the inter-ap handoffs. The only thing that should happen if you have weak GSM coverage is a call drop.

[DrDeke]

Yeah, it does sound like the problem probably has something to do with a multi-AP environment. However, it's strange that it happens when the phone is trying to hand off from GSM to UMA, instead of when trying to hand off from one UMA AP to another.

In any case, I've got more troubleshooting to do next week when I'm back at the locations where this happens.

[John Clark]

Just keep in mind that the wifi BB's are brand new technology and have only had a couple of OS updates since their inception. Hopefully, when OS 4.5 comes out there will be enhancements to the wifi's capability and compatiblity.

[DrDeke]

Oh, definitely. And overall, I'm thrilled at the UMA/GAN capability of my phone as-is. It gives me much better service at my job and at several other places than I could get from any other carrier.

Even so, I would like to see this bug fixed if possible, and I figure the more I can narrow it down, the more useful a report I might be able to make to T-Mobile or RIM about it.

That's one of the reasons it's useful to post about it here; other people (you, so far) come up with scenarios that I can either rule in or rule out, that I hadn't necessarily thought to check yet myself .

[The1Zbo]

I have had this same problem with the hand off from GSM to UMA and the other way around. I notice it more with the hand off from UMA to GSM. I have spent a lot of time on the phone with T-Mobile before one of the customer service reps stated that this is a known problem and they are hoping it will be resolved with the new software update for the curve. But of course no one could tell me any idea when the release date might be.