Connecting to foreign network when abroad

not sure if this is what you are after..
Before you head off abroad, check your network settings. To do this, go to Settings > Mobile Data. Next to Mobile Data Options it will say either Roaming On or Roaming Off. If it says On and you want to make sure you don't spend any extra cash on data while you're abroad, tap this and set it to off.24 Jul 2017

How to avoid iPhone data roaming charges, and how EU rules affect ...

https://www.macworld.co.uk/.../how-avoid-data-roaming-charges-iphone-while-abroad-....
or go to this link.
How do turn off roaming when abroad Google Search

Data roaming is simply cellular internet data but using out of your country. For ex. when you go on holidays to Spain you can use cellular internet from roaming. Roaming is for calls and sms too. And important thing is that roaming is much more expensive then normal in your country

If you need to stop Roaming phone signal while visiting abroad,You should keep in mind the following instructions
1.Turn your voicemail off
2.Just switch Data Roaming off with a help of your service provider.
3.Try to access network through Wi-Fi while visiting abroad.
4.You can also avoid roaming by use the local carrier sim card,which is available in that country.Before put local carrier,Make sure your phone is unlocked or not.If it's restricted by some network,try to unlock your phone using
SuperUnlockCodes.com

Yes,It will work.But Roaming charges will be applicable.
If you need to stop Roaming phone signal while visiting abroad,You should keep in mind the following instructions
1.Turn your voicemail off
2.Just switch Data Roaming off with a help of your service provider.
3.Try to access network through Wi-Fi while visiting abroad.
4.You can also avoid roaming by use the local carrier sim card,which is available in that country.Before put local carrier,Make sure your phone is unlocked or not.If it's restricted by some network,try to unlock your phone using
Unlocking4U.com

If you need to stop Roaming phone signal while visiting abroad,You should keep in mind the following instructions
1.Turn your voicemail off
2.Just switch Data Roaming off with a help of your service provider.
3.Try to access network through Wi-Fi while visiting abroad.
4.You can also avoid roaming by use the local carrier sim card,which is available in that country.Before put local carrier,Make sure your phone is unlocked or not.If it's restricted by some network,try to unlock your phone using
Unlocking4U.com

This is pretty much what you need to do. Just turn off all the roaming features. However when you roam it typically means you dont have service through Sprint so dont be surprised if when you turn off roaming capabilities your phone doesn't get ANY signal. Here's the link to your phones manual page 112 is about roaming.


Setting Roam Mode
Your phone allows you to control your roaming
capabilities. By using the Roaming menu option, you
can determine which signals your phone accepts.
Choose from two different settings on your phone to
control your roaming experience.
1. Press > Settings > More... > Roaming > Set Mode.
2. Highlight an option and press .
n Sprint Only to access only the Sprint network and
prevent roaming on other networks.
n Automatic to seek service on the Nationwide Sprint
Network. When Sprint service is unavailable, the
phone searches for an alternate service.
Call Guard
Your phone has two ways of alerting you when you are
roaming off the Nationwide Sprint Network: the
onscreen roaming icon and Call Guard. Call Guard
makes it easy to manage your roaming by requiring an
extra step before you can place or answer a roaming
call. (This additional step is not required when you make
or receive calls while on the Nationwide Sprint Network.)
To turn Call Guard on or off:
1. Press > Settings > More... > Roaming >
Call Guard.
2. Select On or Off.
To place roaming calls with Call Guard on:
1. From standby mode, dial 1 + area code + the
seven-digit number and press .
2. Read the message and press .
Note Call Guard is turned on by default on yourphone.

To answer incoming roaming calls with Call Guard on:
1. Press .
2. Read the message and press .
Data Roam Guard
Depending on service availability and roaming
agreements, yourphone may be able to access data
services while roaming on certain other networks. You
can set your phone to alert you when you are roaming
off the Nationwide Sprint Network and try to use data
services such as messaging.
To set your Data Roam Guard notification:
1. Press > Settings > More... > Roaming >
Data Roaming.
2. Highlight an option and press .
n Always Ask (default mode) sets your phone's Data
Roam Guard feature on. You will see a prompt that
will require you to respond anytime you access
data services while roaming.
n NeverAsk turns your phone's Data Roam Guard
feature off. Your phone will not notify you of your
roaming status when you access data services.
Touse data services when Data Roam Guard is active:
© When a notification appears informing you that data
roam charges may apply, press ROAM (left softkey)
to connect.
Note If the Call Guard feature is set to On, you need to
take extra steps to make and receive roaming calls.

Hi Nena,

While I do have some ideas on things to try, I must admit my experience in dealing with international messaging is quite slim. I would highly recommend that you contact your mobile phone carrier's support department, and I imagine they would be able to help you out rather quickly (while I may have you on a wild goose chase).

well he would have to call vodafone and have them activate the roam feature for him.