This issue has cropped up many times here on DevForums. Someone recently opened a DTS tech support incident about it, and I used that as an opportunity to post a definitive response here. If you have questions or comments about this, start a new thread and tag it with Network so that I see it. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" iOS Network Signal Strength The iOS SDK has no general-purpose API that returns Wi-Fi or cellular signal strength in real time. Given that this has been the case for more than 10 years, it’s safe to assume that it’s not an accidental omission but a deliberate design choice. For information about the Wi-Fi APIs that are available on iOS, see TN3111 iOS Wi-Fi API overview. Network performance Most folks who ask about this are trying to use the signal strength to estimate network performance. This is a technique that I specifically recommend against. That’s because it produces both false positives and false negatives: The network signal might be weak and yet your app has excellent connectivity. For example, an iOS device on stage at WWDC might have terrible WWAN and Wi-Fi signal but that doesn’t matter because it’s connected to the Ethernet. The network signal might be strong and yet your app has very poor connectivity. For example, if you’re on a train, Wi-Fi signal might be strong in each carriage but the overall connection to the Internet is poor because it’s provided by a single over-stretched WWAN. The only good way to determine whether connectivity is good is to run a network request and see how it performs. If you’re issuing a lot of requests, use the performance of those requests to build a running estimate of how well the network is doing. Indeed, Apple practices what we preach here: This is exactly how HTTP Live Streaming works. Remember that network performance can change from moment to moment. The user’s train might enter or leave a tunnel, the user might step into a lift, and so on. If you build code to estimate the network performance, make sure it reacts to such changes. Keeping all of the above in mind, iOS 26 beta has two new APIs related to this issue: Network framework now offers a linkQuality property. See this post for my take on how to use this effectively. The WirelessInsights framework can notify you of anticipated WWAN condition changes. But what about this code I found on the ’net? Over the years various folks have used various unsupported techniques to get around this limitation. If you find code on the ’net that, say, uses KVC to read undocumented properties, or grovels through system logs, or walks the view hierarchy of the status bar, don’t use it. Such techniques are unsupported and, assuming they haven’t broken yet, are likely to break in the future. But what about Hotspot Helper? Hotspot Helper does have an API to read Wi-Fi signal strength, namely, the signalStrength property. However, this is not a general-purpose API. Like the rest of Hotspot Helper, this is tied to the specific use case for which it was designed. This value only updates in real time for networks that your hotspot helper is managing, as indicated by the isChosenHelper property. But what about MetricKit? MetricKit is so cool. Amongst other things, it supports the MXCellularConditionMetric payload, which holds a summary of the cellular conditions while your app was running. However, this is not a real-time signal strength value. But what if I’m working for a carrier? This post is about APIs in the iOS SDK. If you’re working for a carrier, discuss your requirements with your carrier’s contact at Apple. Revision History 2025-07-02 Updated to cover new features in the iOS 16 beta. Made other minor editorial changes. 2022-12-01 First posted.

I'm trying to create a dialer app for iOS that will make verified cellular, not voip, calls by registering the calls on my server with an option for passphrase offline verification. This means that I want to build a dialer with a nice UX, so I'm trying to use the new default dialer capability. I've read https://developer.apple.com/documentation/livecommunicationkit/preparing-your-app-to-be-the-default-dialer-app which links to https://developer.apple.com/documentation/livecommunicationkit/startcellularconversationaction for starting a call, but when I try to actually use it in my app it says "Cannot find type 'TelephonyConversationManager' in scope" and similar, despite importing LiveCommunicationKit. Is there a default dialer example app & xcode project I can look at for how this should be set up? As I understood it I should be able to use these from iOS 18.2, and I'm targeting that version in my project. The page for StartCellularConversationAction says Beta 26.0 though, have I misunderstood something? does some flag need to be set in my xcode to be able to use this? I read that all test devices need to be in the EU, that should not be the problem.

Hello, I noticed the new entitlement in iOS 26 under LiveCommunicationKit: Preparing your app to be the default dialer app. My question is about eligibility: If a developer account is registered in the EU, can any app add the Default Dialer capability, or is it restricted only to apps that provide real calling/communication functionality (e.g., WhatsApp, Telegram, Skype)? If granted, does this capability allow the app to make/receive cellular calls and access call history, or is it limited only to VoIP-style scenarios through CallKit integration? What are the minimum functionalities required to support this feature (e.g., having a dial pad, call history screen, etc.)? Why must the developer account be registered in the EU to use this entitlement? Thanks in advance for the clarification!

I've been trying to understand what kind of UX is available if my app is using the default-dialer capability. I have found https://developer.apple.com/documentation/livecommunicationkit/preparing-your-app-to-be-the-default-dialer-app and I am in the EU. On android I built the UX I want and it's quite neat, so now I'm trying to work. out what I can get on iOS. Because the product is kind of worthless with just android. I have built a simple dialer ux with a numberpad, contact lookup etc. Then when the user presses the Call button does it have to pop up the system prompt "Call number"? Does it have to swap over to the system ui for the actual call? So there's no way to show information about the call, during the call? Or am I using the frameworks incorrectly? I am very new to iOS development. TrueCaller and others show validation, but as I understand it they pre-fetch all the data, I can't do that.

We have received some information that with the release of iOS 18, there have been notable changes in how this API behaves, can apple team shed some light on this? on ios 17 this worked without much issues, what has changed on ios 18?

I have a question. I work for a mobile operator, and when you insert the SIM, the default APN is automatically configured. However, afterward, using the internal Device Manager platform, we send the corresponding APN of an MVNO to that MSISDN. However, the iPhone device (any model, recent iOS versions) receives the notification of the APN change, but it doesn't reflect the change in the APN settings menu. Do you know how we could make the iPhone device reflect the APN change?

Hi, We have a need to provide SIM verification. At present, accessing the phone number bound to the device is not programmatically accessible. Would Apple consider exposing this API via a user consent? Otherwise, what is the suggested approach to verify the SIM card is the correct phone number on an iOS device?

Hello, I am working to integrate the new com.apple.developer.networking.carrier-constrained.app-optimized entitlement in my iOS 26 app so that my app can use a carrier-provided satellite network, and want to confirm my understanding of how to detect and optimize for satellite network conditions. (Ref: https://developer.apple.com/documentation/bundleresources/entitlements/com.apple.developer.networking.carrier-constrained.app-optimized ) My current approach: I plan to set the entitlement to true once my app is optimized for satellite networks. To detect if the device is connected to a satellite network, I intend to use the Network framework’s NWPath properties: isUltraConstrained — I understand this should be set to true when the device is connected to a satellite network. (Ref: https://developer.apple.com/documentation/network/nwpath/isultraconstrained ) linkQuality == .minimal — I believe this will also be set in satellite scenarios, though it may not be exclusive to satellite connections. (Ref: https://developer.apple.com/documentation/network/nwpath/linkquality-swift.enum/minimal ) Questions: Is it correct that isUltraConstrained will reliably indicate a satellite connection? Should I also check for linkQuality == .minimal, or is isUltraConstrained sufficient? Are there any additional APIs or best practices for detecting and optimizing for satellite connectivity that I should be aware of? Thank you for confirming whether my understanding and approach are correct, and for any additional guidance.

I'm currently experimenting with TelephonyMessagingKit on iOS 26 Beta 3 (in the EU). I've managed to register my example project as the default Carrier messaging app, and sending/receiving SMS inside the app also appeared to work. However, I do not see any way to receive notifications/messages while the app is not running. Is this intentional? Not being able to notify users about an incoming message would be a competitive disadvantage compared to Apple's messages app, which is why I'd expect there to be an API to do this, given the EU rules. I'd appreciate any help here. Thanks!

I am developing a VoIP application that uses NetworkExtension (Local PUSH function) And VoIP(APNs) PUSH. Since iPhone X, iPhones have supported eSIM, allowing for the simultaneous use of a physical SIM and an eSIM. Consequently, users of our VoIP app have requested the ability to lock the network used by the VoIP app to either the eSIM or the physical SIM. Our VoIP app utilizes the network through the socket API. Is there an API in the iOS SDK to lock the network used via sockets to either the eSIM or the physical SIM? In other words, we would like to be able to retrieve the IP address assigned to the eSIM or the physical SIM in advance, and know which IP address is assigned to which SIM. Are there any such APIs available (that are not "Deprecated")

Hi Forum, We’re building a security-focused SDK for iOS that includes SIM Binding and SIM Swap detection to help prevent fraud and unauthorised device access, particularly in the context of banking and fintech apps. We understand that iOS limits access to SIM-level data, and that previously available APIs (such as those in CoreTelephony, now deprecated from iOS 16 onwards) provide only limited support for these use cases. We have a few questions and would appreciate any guidance from the community or Apple engineers: Q1. Are there any best practices or Apple-recommended approaches for binding a SIM to a device or user account? Q2. Is there a reliable way to detect a SIM swap when the app is not running (e.g., via system callback, entitlement, or background mechanism)? Q3. Are fields like GID1, GID2, or ICCID accessible through any public APIs or entitlements (such as com.apple.coretelephony.IdentityAccess)? If so, what is the process to request access? Q4. For dual SIM and eSIM scenarios, is there a documented approach to identify which SIM is active or whether a SIM slot has changed? Q5. In a banking or regulated environment, is it possible for an app vendor (e.g., a bank) to acquire certain entitlements from Apple and securely expose that information to a security SDK like ours? What would be the compliant or recommended way to structure such a partnership? Thanks in advance for any insights!

I am checking the response of DeviceInformation Command to collect network information from iPad. On iPad(iPad Pro 11, M4) devices that use WiFi without inserting Usim or Esim, network values ​​such as CurrentMCC and ICCID are received in response to the DeviceInformation command. cf.)Even though it may be garbage value, I blurred the unique information just in case. <key>ServiceSubscriptions</key> <array> <dict> <key>CarrierSettingsVersion</key> <string>61.0</string> <key>CurrentCarrierNetwork</key> <string></string> <key>CurrentMCC</key> <string>450</string> <key>CurrentMNC</key> <string>08</string> <key>EID</key> <string>blah blah</string> <key>ICCID</key> <string>blah balh</string> <key>IMEI</key> <string>blah blah</string> <key>IsDataPreferred</key> <true/> <key>IsRoaming</key> <true/> <key>IsVoicePreferred</key> <false/> <key>Label</key> <string>Provisioning</string> <key>LabelID</key> <string>00000000-0000-0000-0000-000000000000</string> <key>PhoneNumber</key> <string></string> <key>Slot</key> <string>CTSubscriptionSlotOne</string> <key>SubscriberCarrierNetwork</key> <string>iPad</string> </dict> </array> This is a bit weird. If I collect the same information from an iPhone(iPhone 15 Pro Max) that only uses wifi and does not use Usim or Esim, it does not respond with values ​​like ICCID, CurrentMCC, etc. <key>ServiceSubscriptions</key> <array> <dict> <key>IMEI</key> <string>blah blah</string> <key>Slot</key> <string>CTSubscriptionSlotOne</string> </dict> <dict> <key>EID</key> <string>blah blah</string> <key>IMEI</key> <string>blah blah</string> <key>Slot</key> <string>CTSubscriptionSlotTwo</string> </dict> </array> I'm confused by the network information collected. Is there a reason why the collected network information of iPad and iPhone are different?

Before iOS16, we can use https://developer.apple.com/documentation/coretelephony/ctcarrier But after iOS this is deprecated and has no replacement. There are some discussions on it, eg. https://developer.apple.com/forums/thread/714876 https://developer.apple.com/forums/thread/770400 Now I asked AI, then it provided this solution, to check the serviceCurrentRadioAccessTechnology, so it this ok to check the SIM card status? var hasSIMCard = false let info = CTTelephonyNetworkInfo() if let rat = info.serviceCurrentRadioAccessTechnology, rat.values.contains(where: { !$0.isEmpty }) { hasSIMCard = true. // has RAT } BTW, I can see a lot of changes in the Core Telephony framework. https://developer.apple.com/documentation/coretelephony 1.isSIMInserted https://developer.apple.com/documentation/coretelephony/ctsubscriber/issiminserted A Boolean property that indicates whether a SIM is present. iOS 18.0+ iPadOS 18.0+ This value property is true if the system finds a SIM matching the Info.plist carrier information (MCC / MNC / GID1 / GID2). Is this ok to check SIM insert status, this seems must preconfig some info in the info.plist. 2.iOS26 provide CTCellularPlanStatus https://developer.apple.com/documentation/coretelephony/ctcellularplanstatus Can I use this to check SIM status?

Hello, I am developing a private internal Flutter app for our customer, which will not be published on the Apple Store. One of the key features of this app is to collect RF strength metrics to share user experience with the network. For Android, we successfully implemented the required functionality and are able to collect the following metrics: Signal strength level (0-4) Signal strength in dBm RSSI RSRQ Cell ID Location Area Code Carrier name Mobile country code Mobile network code Radio access technology Connection status Duplex mode However, for iOS, we are facing challenges with CoreTelephony, which is not returning the necessary data. We are aware that CoreTelephony is deprecated and are looking for alternatives. We noticed that a lot of the information we need is available via FTMInternal-4. Is there a way to access this data for a private app? Are there any other recommended approaches or frameworks that can be used to gather cellular network information on iOS for an app that won't be distributed via the Apple Store? my swift code import Foundation import CoreTelephony class RfSignalStrengthImpl: RfSignalStrengthApi { func getCellularSignalStrength(completion: @escaping (Result<CellularSignalStrength, Error>) -> Void) { let networkInfo = CTTelephonyNetworkInfo() guard let carrier = networkInfo.serviceSubscriberCellularProviders?.values.first else { completion(.failure(NSError(domain: "com.xxxx.yyyy", code: 0, userInfo: [NSLocalizedDescriptionKey: "Carrier not found"]))) return } let carrierName = carrier.carrierName ?? "Unknown" let mobileCountryCode = carrier.mobileCountryCode ?? "Unknown" let mobileNetworkCode = carrier.mobileNetworkCode ?? "Unknown" let radioAccessTechnology = networkInfo.serviceCurrentRadioAccessTechnology?.values.first ?? "Unknown" var connectionStatus = "Unknown" ... ... } Thank you for your assistance.

My app requirement is to check that User is on call while doing transaction. If user on call then we need to show Caution alert. For this requirement we used CallKit to detect Call status and it's working fine but recently Apple has rejected the application because of Callkit that is banned in China. Could you please provide any solution to check the Call Status only.

I’m working on carrier services that require ICCID. Is there a special entitlement to be able to access this info? What’s the process to request authorization if available?

We are currently working on deploying a Java Card applet onto the eSIM (eUICC) inside an iPhone. According to the GSMA SGP specifications, the eUICC is expected to support Java Card 3.0.5 Classic Edition. As defined in the Java Card 3.0.5 specification, the javacardx.crypto package should support standard algorithms including MessageDigest.ALG_HMAC_SHA_512. However, during our testing on the iPhone's embedded eSIM, we found that ALG_HMAC_SHA_512 appears to be unsupported or disabled. The same applet functions correctly on external Java Card platforms that support Java Card 3.0.5, leading us to believe that this is a restriction specific to the iPhone’s eUICC implementation. Our main questions are: Why is ALG_HMAC_SHA_512, which is part of the standard Java Card 3.0.5 specification, not available on the iPhone eSIM? Has Apple imposed any internal restrictions or exclusions on certain crypto algorithms for security, performance, or compliance reasons? Is there a list or documentation of supported and unsupported Java Card APIs or algorithms on the eUICC used in iPhones? Any insights from Apple engineers or other developers with experience on this topic would be greatly appreciated. Thank you in advance!

DYLD, symbol '_CTRadioAccessTechnologyNR' not found, expected in '/System/Library/Frameworks/CoreTelephony.framework/CoreTelephony'

I have a question about the default calling function that is supported by third-party apps on iOS from 18.2. In most cases, it works normally with the default calling app setting, but the problem occurs when connected to the vehicle via Bluetooth. Install the app that sets the default calling app on the device. Keep the phone locked. Connect the Bluetooth to the vehicle. Try to make a call using the phone button on the vehicle's steering wheel. When trying to make a call from the vehicle, the call fails (It seems that the app cannot be opened when the phone is locked even if the default calling app setting is on.) When you unlock the phone and turn on the app, the call is made. As far as I understand, if the app scheme is called with tel:// when set as the default calling app, it only proceeds with the intent connection to the app set as the default calling app, and the permissions that Apple's default call app has cannot be used. Accordingly, my questions are as follows: Is there a way to make a call with an external phone call input when locked on device? If 1 is not possible, can you provide a branch to Apple's default call app (telephony://) in the above situation?

My main app does have entitlement to access Coretelphony, i would like to use the same with Appclips, though i was able to add the entitlement to appclip profile, i am unable to create archive for Testflight, i am seeing missing esim profile capabilities, is this not supported in appclips at the moment?