diff --git a/pySim/ts_51_011.py b/pySim/ts_51_011.py
index 754d57f..1cec91f 100644
--- a/pySim/ts_51_011.py
+++ b/pySim/ts_51_011.py
@@ -249,3 +249,66 @@
 'MMSUP':  DF['GSM']+[EF_num['MMSUP']],
 'MMSUCP': DF['GSM']+[EF_num['MMSUCP']],
 }
+
+# Mapping between SIM Service Number and its description
+EF_SST_map = {
+	1: 'CHV1 disable function',
+	2: 'Abbreviated Dialling Numbers (ADN)',
+	3: 'Fixed Dialling Numbers (FDN)',
+	4: 'Short Message Storage (SMS)',
+	5: 'Advice of Charge (AoC)',
+	6: 'Capability Configuration Parameters (CCP)',
+	7: 'PLMN selector',
+	8: 'RFU',
+	9: 'MSISDN',
+	10: 'Extension1',
+	11: 'Extension2',
+	12: 'SMS Parameters',
+	13: 'Last Number Dialled (LND)',
+	14: 'Cell Broadcast Message Identifier',
+	15: 'Group Identifier Level 1',
+	16: 'Group Identifier Level 2',
+	17: 'Service Provider Name',
+	18: 'Service Dialling Numbers (SDN)',
+	19: 'Extension3',
+	20: 'RFU',
+	21: 'VGCS Group Identifier List (EFVGCS and EFVGCSS)',
+	22: 'VBS Group Identifier List (EFVBS and EFVBSS)',
+	23: 'enhanced Multi-Level Precedence and Pre-emption Service',
+	24: 'Automatic Answer for eMLPP',
+	25: 'Data download via SMS-CB',
+	26: 'Data download via SMS-PP',
+	27: 'Menu selection',
+	28: 'Call control',
+	29: 'Proactive SIM',
+	30: 'Cell Broadcast Message Identifier Ranges',
+	31: 'Barred Dialling Numbers (BDN)',
+	32: 'Extension4',
+	33: 'De-personalization Control Keys',
+	34: 'Co-operative Network List',
+	35: 'Short Message Status Reports',
+	36: 'Network\'s indication of alerting in the MS',
+	37: 'Mobile Originated Short Message control by SIM',
+	38: 'GPRS',
+	39: 'Image (IMG)',
+	40: 'SoLSA (Support of Local Service Area)',
+	41: 'USSD string data object supported in Call Control',
+	42: 'RUN AT COMMAND command',
+	43: 'User controlled PLMN Selector with Access Technology',
+	44: 'Operator controlled PLMN Selector with Access Technology',
+	45: 'HPLMN Selector with Access Technology',
+	46: 'CPBCCH Information',
+	47: 'Investigation Scan',
+	48: 'Extended Capability Configuration Parameters',
+	49: 'MExE',
+	50: 'Reserved and shall be ignored',
+	51: 'PLMN Network Name',
+	52: 'Operator PLMN List',
+	53: 'Mailbox Dialling Numbers',
+	54: 'Message Waiting Indication Status',
+	55: 'Call Forwarding Indication Status',
+	56: 'Service Provider Display Information',
+	57: 'Multimedia Messaging Service (MMS)',
+	58: 'Extension 8',
+	59: 'MMS User Connectivity Parameters',
+}
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