Not a few people have certain difficulties in dealing with the Administration's procedures, especially if they try to do them from home without going to an office.In these situations, the option of being able to use our mobile phone to carry out these procedures can be especially useful.Social Security allows procedures to be carried out via SMS by sending a single-use code to the mobile phone with which the procedure of interest to the citizen can be accessed.The agency ensures on its website that this system "bases the security of the user's identification on the user's knowledge of a series of personal data and on the possession of the mobile device."The only downside is that in order to carry out the procedures with Social Security via SMS, the mobile phone number must be registered in the Social Security database, since otherwise the agency will not be able to send the code to the citizen. and the process cannot be carried out.There are several ways to communicate to Social Security what our mobile phone number is and leave it registered in its database.They are equally valid and simply differ in their speed and access methods.-The fastest alternative is to enter the 'Personal data' area of ​​the Import@ss platform to carry out online procedures with Social Security.Available at this link, it allows changes to be made regarding the mobile phone but also other important data such as the address, the landline telephone number or the email address.However, this option has a handicap: to be able to access this service you need to have a digital certificate (so you can get it in four simple steps), use Cl@ve (so you can register to obtain a Cl@ve PIN or permanent ) or an electronic ID.It makes a certain sense that people who opt for the SMS route do so in order not to use these forms of access to procedures, so there is another possibility for them.-You can register your mobile phone number in the Social Security database by filling in the TA.1 model, which can be downloaded at this link.In the reason for the communication, the citizen must indicate that it is 'Data Variation'.All the necessary contact and personal data must appear in the form, as well as the information regarding the new telephone number to be registered.When the TA.1 form is correctly completed, it must be saved on the computer and the Import@ss 'Send a request' service must be used, which does not require access methods.You must attach the TA.1 model, indicate the DNI or NIE, an email address and a photograph to prove the identity of the applicant.The process can be done by clicking on this link.