diff --git a/pySim-smpp2sim.py b/pySim-smpp2sim.py
index f7a45f5a..95b9ccd5 100755
--- a/pySim-smpp2sim.py
+++ b/pySim-smpp2sim.py
@@ -55,6 +55,7 @@ from pySim.transport import LinkBase, ProactiveHandler, argparse_add_reader_args
 from pySim.commands import SimCardCommands
 from pySim.cards import UiccCardBase
 from pySim.exceptions import *
+from pySim.cat import sms_pp_download_envelope
 from pySim.cat import ProactiveCommand, SendShortMessage, SMS_TPDU, SMSPPDownload, BearerDescription
 from pySim.cat import DeviceIdentities, Address, OtherAddress, UiccTransportLevel, BufferSize
 from pySim.cat import ChannelStatus, ChannelData, ChannelDataLength
@@ -169,10 +170,7 @@ class MyServer:
         tpdu = SMS_DELIVER.from_smpp_submit(pdu)
         logger.info(tpdu)
         # 2) wrap into the CAT ENVELOPE for SMS-PP-Download
-        tpdu_ie = SMS_TPDU(decoded={'tpdu': b2h(tpdu.to_bytes())})
-        addr_ie = Address(decoded={'ton_npi': {'ext':False, 'type_of_number':'unknown', 'numbering_plan_id':'unknown'}, 'call_number': '0123456'})
-        dev_ids = DeviceIdentities(decoded={'source_dev_id': 'network', 'dest_dev_id': 'uicc'})
-        sms_dl = SMSPPDownload(children=[dev_ids, addr_ie, tpdu_ie])
+        sms_dl = sms_pp_download_envelope(tpdu)
         # 3) send to the card
         envelope_hex = b2h(sms_dl.to_tlv())
         logger.info("ENVELOPE: %s" % envelope_hex)
diff --git a/pySim/cat.py b/pySim/cat.py
index d755545a..89590040 100644
--- a/pySim/cat.py
+++ b/pySim/cat.py
@@ -763,6 +763,22 @@ class SMSPPDownload(BER_TLV_IE, tag=0xD1,
                     nested=[DeviceIdentities, Address, SMS_TPDU]):
     pass
 
+
+def sms_pp_download_envelope(tpdu, call_number: str = '0123456') -> SMSPPDownload:
+    """TS 31.111 Section 7.1.1.2 wrap of a SMS-DELIVER TPDU in the ENVELOPE (SMS-PP Download)
+     call_number :
+     SMSC address to report, defined in TS 31.111 7.1.1.2 as
+    "the RP_Originating_Address of the Service Centre (TS-Service-Centre-Address, 3GPP TS 24.011)"
+    its presence is Conditional, and the note there says the UICC should be fine
+    if its missing, so for remote management its presence should suffice (?).
+    """
+    return SMSPPDownload(children=[
+        DeviceIdentities(decoded={'source_dev_id': 'network', 'dest_dev_id': 'uicc'}),
+        Address(decoded={'ton_npi': {'ext': False, 'type_of_number': 'unknown',
+                                     'numbering_plan_id': 'unknown'},
+                         'call_number': call_number}),
+        SMS_TPDU(decoded={'tpdu': b2h(tpdu.to_bytes())})])
+
 # TS 101 220 Table 7.17 + 31.111 7.1.1.3
 class SMSCBDownload(BER_TLV_IE, tag=0xD2,
                     nested=[DeviceIdentities, CBSPage]):