T-Mobile and AT&T Customers With iSocket 3G

iSocket Smart Plug SMS Manager Android
Posted (or last update) , by Denis Sokol

UPDATE: We can no longer guarantee operation of the device with SIM-cards purchased directly from T-Mobile or AT&T. Please use Truphone SIM cards. Read our FAQ here. Below is the old article.


Our customers have tested iSocket using SIM cards from both AT&T and T-Mobile and the device works well with both these operators. However the activating process could be a challenge – please read below. Also, the tariff schedules of these operators might not satisfy all customers, especially if a customer does not have a contract with T-Mobile or AT&T.

If you are a Verizon customer you can manage iSocket from your Verizon phone, but you cannot connect the iSocket 3G to Verizon’s network, because their network is a different standard to T-Mobile or AT&T. You have to buy a SIM card for iSocket 3G – read this post.

NOTE! You do not need to buy SIM cards from T-Mobile or AT&T directly if you do not wish to – read this post. If you want to go with T-Mobile or AT&T directly this will be an adventure for you – read below.

How to use iSocket 3G with T-Mobile

At the time of writing I see that T-Mobile have a "Prepaid - Pay-As-You-Go" plan which costs 0.1$ per text and you pay $10 in advance for airtime, which however expires after 90 days. This, in fact, means that you have to spend $10 every 3 months and for those $10 you get 100 texts for the iSocket. There was also a "Prepaid - Pay by the Day" plan where you pay $1 per day plan for unlimited texting. This might be useful if you want to monitor a remote cabin or use iSocket for other purposes on a certain day of the month. On that day you will be charged $1 from your prepayment and you can send as many texts as you want in that day. On other days if you send nothing, you pay nothing. You need to be careful with this type of plan if you expect to send texts every day! Monthly plans and contract plans are more expensive, so I don’t consider them. I cannot follow all the changes that T-Mobile make in their tariffs, so please check the T-Mobile website to see the current situation.

Note: you do not need data to work with iSocket 3G, only texts and call (or voice) capability if you want to perform some operations by call. You might want a data plan if you decide to use Open API, remote firmware update or other Internet of Things features of iSocket 3G.

At the time of writing T-Mobile were offering SIM cards on a so-called Activation Kit on their website. They did not charge for the SIM card itself and there were specific actions required to combine the purchased Kit with a prepaid plan. I cannot follow all the changes so I encourage you to check the T-Mobile website. Activation of the SIM card was a challenge at the time of writing. I will describe our experience, but please check if the situation has changed after you have read it.

T-Mobile requires you to activate the SIM Card with an unlocked cell phone using the IMEI number of the phone. They assume that you are buying this card for an unlocked cell phone. Our iSocket 3G unit operates exactly the same way as an unlocked phone - our unit is in fact an unlocked cellular device, but it has no display screen. The problem arises when T-Mobile, after you have activated the card, sends you the temporary password. They assume that they are texting it to the display of a cellular phone that you are currently activating. But you are not using a phone with a display. This is the problem. The only way to receive the password is via SMS text. And you will need this password to go online to fill in the card, otherwise it will be de-activated later. How to overcome this? There are only a few options: either borrow an unlocked cell phone for activation purposes from someone, or ask the T-Mobile specialists in the local T-Mobile store to activate the card for you. There are times when the store attendant might not have the necessary experience, especially if you present him/her with the card purchased from the Internet and they don’t sell similar cards in their office.

As soon as you have unlocked cell phone, insert your purchased SIM card and go through the activation process on the T-Mobile website. When you are asked to add the Phone serial number (IMEI) you have to add the IMEI number that is written on the label on the back of the iSocket (15 digits). After activation you will get a text with the temporary password to the phone. Your card is now activated and you can insert it into the iSocket. When you have this temporary password you may go online. Use the phone number given to you for your login and the temporary password to change passwords and manage your account. Once you are at the "manage your account" area of their web page, we would suggest you give them credit card details. They will post $10 on it whenever you run low on time or out of days. Thus you can always keep the subscription active automatically.

Keep your card active or you will need to go through the activation process again after a certain period if it expires.

Some customers who have a contract with T-Mobile were able to buy and add a SIM card to their current subscription for acceptable tariffs and use this card with iSocket. If you are a T-Mobile customer you may consider this option.

NOTE: Disable any voicemail or call-forwarding services! Ask T-Mobile how to do this.

Good luck with your T-Mobile activation adventure! :)

How to use iSocket 3G with AT&T

Some of my customers have contracts with AT&T and they were able to buy a SIM card and add it to their current tariff for free. They have a flat rate plan with AT&T and an extra SIM card follows with that plan. When AT&T ask you for the IMEI number, you should use the number printed on the label at the back of the device.

I have also had some customers who did not have contracts with AT&T and were able to buy a SIM card from AT&T and activate it online without needing to have an unlocked cell phone as described above for T-Mobile.

Note: AT&T require the 3G device to be certified on their network before they will sell you SIM cards in bulk. We will do that certification for iSocket 3G.

Please check what AT&T offer at the moment on their website.

Disable any voicemail or call- forwarding services on SIM card that you insert to iSocket. Read this post for basic information.

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