I have a 3GS (MC) with 4.1 Firmware (8B117) and baseband 06.15.00. My original thought was to jailbreak & unlock the phone so that I can switch from my BB 9700 to this. A few questions from some reading came up along the way which I am hoping other people's experiences can shine a light:

1) Should I stay at 4.1 or go to 4.2.1. If so, should I upgrade the firmware through standard iTunes or use Redsn0w?

2) If I Jailbreak and Unlock the phone, will Push Mail work in this mode? I've read a number of issues but they all seem to be related to the older phones and older OS'. I want to get my GMail on the phone instantly like I do on my BlackBerry.

3) Once Unlocked, I assume I can take my SIM card from my BB 9700 and use it in the 3GS. Any issues here?

Any other technical issues/concerns other than the standard no-support, no warranty... that I should be worried about?

All comments and past experiences are greatly appreciated.

TIA

1) It is widely recommended to stay at 4.1 right now. There *is* an untethered 4.2.1 for old bootrom 3GS models, but even with the untethered jailbreak, software isn't yet compatible, etc. For the most stability, it's recommended you stay on 4.1 at the moment.
2) Yes. Push mail will work. The push issue that most people talk about in hacktivated phones relates more to push notifications and FaceTime activation, both of which are solved with the SAM (Subscriber Activation Module) software that has recently been released.
3) Shouldn't be -- I do this at work all the time. You'll need to ensure that you have a compatible data plan if you want data and visual voicemail to work, but for just making phone calls you can just switch the SIM. I think there's a way for the iPhone to work with the $45 blackberry unlimited (BES, not BIS) service package, but there's little reason to do this as the $30 data plan for the iPhone is more advantageous.

Concerns are that you will need an SHSH to go back to 4.1 if you do something that causes the phone to bootloop -- are you aware of what an SHSH is and how to obtain / what they're used for? If not, take a peek at my signature, I've got a link in there that goes to saurik's discussion on it. Make sure you know what an SHSH is, how it works, and which of them you have available to you, as this will dictate what you can do if your phone ever does bootloop and need to be factory restored.

Good luck!

Originally Posted by pjg61

I have a 3GS (MC) with 4.1 Firmware (8B117) and baseband 06.15.00.

Did you pick this up second hand? No original 3GS will have baseband 06.15.00

MC model means nothing on a 3GS.

Originally Posted by pjg61

Should I stay at 4.1 or go to 4.2.1. If so, should I upgrade the firmware through standard iTunes or use Redsn0w?

You should work out if you are new or old bootrom and also confirm that the previous owner saved a 4.1 SHSH

Originally Posted by pjg61

If I Jailbreak and Unlock the phone, will Push Mail work in this mode? I've read a number of issues but they all seem to be related to the older phones and older OS'. I want to get my GMail on the phone instantly like I do on my BlackBerry.

Yes it will work

Originally Posted by pjg61

Once Unlocked, I assume I can take my SIM card from my BB 9700 and use it in the 3GS. Any issues here?

Most likely - yes you will have no problems. However I recommend that you read up on SAM, poor battery life and hacktivation - here http://www.hackint0sh.org/f204/194306.htm

Originally Posted by Olethros

Did you pick this up second hand? No original 3GS will have baseband 06.15.00

MC model means nothing on a 3GS.

This is an original 3GS 4.1 with 05.14.2 and I had many problems trying to jailbreak it by first upgrading the baseband and then the firmware. Finally, I managed to regress to 4.1 with baseband 06.15.00. I mentioned the model "MC" because throughout my reading, people seemed to say that the "MB" models were easier to jailbreak or less prone to issues. Maybe not true?

Originally Posted by Olethros

You should work out if you are new or old bootrom and also confirm that the previous owner saved a 4.1 SHSH

I never saved the original SHSH blobs. But, now that I am back on 4.1, can I save them or am I screwed because they were never originally saved?

Thanks

MB and MC only applies to Itouch 2nd generation.
To find out if you have SHSH save for each firmware version, get tinyumbrella, read the readme file, run it, click on save SHSH and you will know what you have.

SHSH is very very very important, without it, you will be SOL.

Stay at 4.1 for now.

Originally Posted by dtube

MB and MC only applies to Itouch 2nd generation.
To find out if you have SHSH save for each firmware version, get tinyumbrella, read the readme file, run it, click on save SHSH and you will know what you have.

SHSH is very very very important, without it, you will be SOL.

Stay at 4.1 for now.

I have two SHSHs:

iPhone 3GS 4.1 (8B117)
iPhone 3GS 4.2.1 (8C148a)

Now, I have them saved on my laptop! Thank you to everyone for your guidance. I will now hopefully proceed on the right track.

dtube, olethros, n1ckn4m3,

Thanks for your comments. With 4.1 and 06.15.00, I was able to Jailbreak (with redsn0w) and Unlock (with ultrasn0w) my phone with 0 problems. Everything went super smooth as it should. I also installed SAM, set my phone up with GoogleSync and now get all my mail instantly on the phone.

Also, it reboots cleanly untethered which I didn't think was possible with the current jailbreak. From what I read, I thought the current jailbreak with 4.1 or 4.2.1 and 06.15.00 requires a tethered reboot.

One related/unrelated question. My Visual Voicemail doesn't work at all. Basically, when I select the Voicemail icon, it simply dials my voicemail on the Rogers network. There seems to be no way to get to the visual voicemail settings. Is this a problem due to the jailbreaking or simply because my carrier thinks I have a Blackberry? Is there something to reset on the iPhone to get my Visual Voicemail working?

Many thanks again for the assistance...

Originally Posted by pjg61

Also, it reboots cleanly untethered which I didn't think was possible with the current jailbreak. From what I read, I thought the current jailbreak with 4.1 or 4.2.1 and 06.15.00 requires a tethered reboot

Only 4.2.1 jailbreak is tethered.

Restoring an iPhone with 6.15 baseband works best with custom IPSW.

Originally Posted by pjg61

One related/unrelated question. My Visual Voicemail doesn't work at all. Basically, when I select the Voicemail icon, it simply dials my voicemail on the Rogers network.

Did VVM work previously? I know there has to be a flag set on their end and, if I recall, it also is based on the APN settings and the type-mask setting specifically in the APN settings will dictate and determine what functions are available on the network you're choosing (MMS, Tethering, VVM, etc.).

I would check there, but admittedly I'm not 100% certain this will solve you issue, just a thought.

Originally Posted by n1ckn4m3

Did VVM work previously? I know there has to be a flag set on their end and, if I recall, it also is based on the APN settings and the type-mask setting specifically in the APN settings will dictate and determine what functions are available on the network you're choosing (MMS, Tethering, VVM, etc.).

I would check there, but admittedly I'm not 100% certain this will solve you issue, just a thought.

I moved my SIM card from a BlackBerry 9700 to the 3GS. I will probably call my carrier next week and switch my data plan to an iPhone pland and I am assuming that this will enable VMM.

Btw, do carriers validate that this is an un-jailbreaked phone? Or is there nothing to worry about and I can simply change my data plan?