SMS sender phone number issue

Hello,
I am facing an issue with getting SMS sender’s phone number.
I am using 751U-2HnD running software version 6.39.2 (stable) with 3G HUAWEI modem.
I send an SMS from my phone and I can see it in the Inbox window on the router. Then I run this command_1:

:global phone [/tool sms inbox get number=0 value-name=phone]; :log info message=$phone;

And $phone variable appears to be empty:

14:25:01 script,info

But if I run this command_2 :

/tool sms inbox print

And then command_1 again, I see that $phone is a phone number that I need:

14:26:20 script,info +371XXXXXXXX

Any ideas? How can I solve this?
Thank you!

Please somebody help me about this topic