Travel Technology - T-Mobile charged me for SMS using another SIM card

Does anyone know how this is possible. I was in HKG earlier this month and bought a Peoples SIM card to text and make calls. I got my bill today and for each of my outgoing texts, I was charged $0.35. The time reported for each of the texts was about 18-24 hours after they were actually sent.

I'm not really concerned about the $$$, but I'm curious how T-Mobile is able to know about and charge for this. I did use my T-Mobile SIM periodically to download my email to my Blackberry, so maybe they were able to connect my phone through the Peoples network?

Any ideas? :confused::confused::confused:

I'm guessing the phone's GPRS profile was not updated so the SMS went through T-mobile's gateway instead of People's.

Like the previous poster said; the phone was still set to the T-mobile SMS gateway, so when you sent them using the HKG sim they failed to be sent (as you can't send through an operator gateway using a sim not linked to that operator.

So when you popped your T-mobile sim back in the phone it started sending what was in the queue.

I've had this happen too using the UM sim in some of the regular phones. I just forget to change the gateway. I THINK the that the UM+ sim has corrected this though. I might try a trial run.

By now, I just pretty much use a unique phone for my international sims.

Like the previous poster said; the phone was still set to the T-mobile SMS gateway, so when you sent them using the HKG sim they failed to be sent (as you can't send through an operator gateway using a sim not linked to that operator.

So when you popped your T-mobile sim back in the phone it started sending what was in the queue.

I'm pretty sure the texts were sent as I received replies before swapping SIM cards.

In any case, how would I change the SMS gateway?

I'm pretty sure the texts were sent as I received replies before swapping SIM cards.

In any case, how would I change the SMS gateway?

Are you sure that the texts were sent and received with the HK SIM card? Most of the time, if there is a failure to send an SMS message there is rarely an error reported. The majority of time the message will remain in the outbox and the device will continue to try to send the message until successful. There is a timeout period, but I believe it is days and not hours.

The messages were likely sent later when you popped your T-Mobile SIM into your blackberry to check your email or make phone calls with that number.

Many prepaid SIM cards purchased overseas don't always include SMS or international SMS. And as previous posters have noted, you sometimes may need to update your SMS gateway.

Are you certain that your T-Mobile device is unlocked?

In any case, how would I change the SMS gateway?
It varies by the phone model. Phones branded by carriers in the US may have the function hidden away. For example, my T-mobile branded Samsung does not have the GPRS settings accessible through the menu. I have to punch in some nonsense like *#9998*JAVA#.

My unbranded, unlocked Sony Ericssons have the option in the connections menu under phone settings. Sony Ericsson's support page can also send a SMS to your phone and configure the WAP and GPRS settings automatically.

Many prepaid SIM cards purchased overseas don't always include SMS or international SMS. And as previous posters have noted, you sometimes may need to update your SMS gateway.

Are you certain that your T-Mobile device is unlocked?

Yes, the phone is unlocked. The texts did go out immediately as I would send and then get replies. The Peoples SIM did have a SMS plan, so I guess I need to update the SMS gateway for my next trip.

I didn't mention that T-Mobile only charged me for the outbound texts, not incoming. And, I imagine that sending a text from HKG to someone else in HKG, going through the T-Mob network, would cost me more than $0.35, right? The agent told me that the $0.35 is for someone on the T-Mob network to text someone internationally.


It varies by the phone model. Phones branded by carriers in the US may have the function hidden away. For example, my T-mobile branded Samsung does not have the GPRS settings accessible through the menu. I have to punch in some nonsense like *#9998*JAVA#.

My unbranded, unlocked Sony Ericssons have the option in the connections menu under phone settings. Sony Ericsson's support page can also send a SMS to your phone and configure the WAP and GPRS settings automatically.

So, when unlocking your phone and putting in a different carrier's SIM card, the WAP and GPRS gateway don't automatically get reset?

So, when unlocking your phone and putting in a different carrier's SIM card, the WAP and GPRS gateway don't automatically get reset?
Correct. SIM does not contain WAP and GPRS settings. Most prepaid plans don't offer data access, so they just skip the configuration.

A quick check of the specs revealed that SIM's do contain the Short Message Service Center (SMSC) phone number. This setting is ignored when the mobile device sends SMS over GPRS, which seems to be the default these days.

This still doesn't answer the question on how T-mobile knows to bill your account without the SIM. Is it a Sidekick? They are tightly integrated with T-mobile's online services. For example, when you take a picture it is uploaded instantly to the associated account's online album.

Is it a Sidekick?

Nope, a Blackberry Pearl.