NethVoice: Fix call and DTMF URLs for Fanvil Linkvil W611W and W620W #8249

Description

Fanvil Linkvil W611W and W620W Wi-Fi phones require semicolon-separated digits when executing call and DTMF commands via Phone Function URLs.

Fanvil support confirmed that each digit must be separated by ; for these models.

Steps to reproduce

Configure a Fanvil Linkvil W611W or W620W phone.

Execute the currently configured call URL:

http://$PHONE_USER:$PHONE_PASS@$PHONE_IP/cgi-bin/ConfigManApp.com?key=$NUMBER;ENTER

Try dialing 1234 using key=1234;ENTER.

Observe that the phone returns HTTP 200 OK but does not initiate the call.

Expected behavior

The phone successfully places the call using the Phone Function URL.

Actual behavior

The phone returns HTTP 200 OK without placing the call.

Fanvil support confirmed that W611W and W620W require semicolon-separated digits for call and DTMF commands.

For example, dialing 1234 requires:

http://$PHONE_USER:$PHONE_PASS@$PHONE_IP/cgi-bin/ConfigManApp.com?key=1;2;3;4;ENTER

The URL generation logic should be updated to insert ; between digits for these models.