• SDF's C*NET NXX is 333 (ex. +1-333-1000 connects you with our Milliwatt)
• For listings that have enabled 'Direct VoIP' dial extension (@) sip.sdf.org
• Please note that making unsolicited calls may be considered rude=== Test and Service Extensions ===

| Extension | Subscriber | Description | 24/7 |

| 1001 | internal | Date and Time UTC | YES |
| 1002 | internal | Linear Sine Test from 16Hz to 20kHz | YES |
| 1003 | internal | Exponential Sine Test from 16Hz to 20kHz | YES |
| 1004 | internal | Milliwatt (1004Hz @ 0dB) | YES |
| 1005 | internal | Echo Response Test (USA) | YES |
| 1006 | internal | CQ Serenade | YES |
| 1026 | internal | 2600Hz @ 0dB | YES |
| 1030 | internal | Music on Hold | YES |
| 1085 | internal | Voice Mail System | YES |
| 1088 | internal | Conference Bridge (//Press #1 to toggle mute//) | YES |
| 5004 | internal | Milliwatt (1004Hz @ 0dB) (EU) | YES |
| 5005 | internal | Echo Response Test (EU) | YES |
| 5085 | internal | Voice Mail System (EU) | YES |
| 5088 | internal | Conference Bridge (EU) (//Press #1 to toggle mute//) | YES |=== Subscriber Extension Directory ===
| **Extension** | **UTC +/- Offset** | **Subscriber** | **Description** | **Unsolicited Calls** | **Direct VoIP** |
| 1100 | -08:00 | smj | Nokia e70 S60 | YES | YES |
| 1101 | -07:00 | br | Nokia N900, Ekiga | YES |  |
| 1103 | +00:00 | yargo | linphone | YES |  |
| 1106 | -06:00 | ecelis | ekiga | YES |  |
| 1107 | -05:00 | nsweeney | iPhone | YES |  |
| 1109 | -08:00 | jgw | Ekiga | YES | NO |
| 1111 | -08:00 | testing | testing | NO |  |
| 1112 | -08:00 | anthonyg | Nexus S, Linphone | YES | YES |
| 1116 | +05:30 | rmj | Blink | YES |  |
| 1118 | +01:00 | vosi | various clients | YES |  |
| 1119 | -05:00 | carbine | Aastra 9133i | YES |  |
| 1120 | +01:00 | bb | Nokia n97 S60 | YES |  |
| 1121 |  | jones | Various Clients | YES |  |
| 1127 | -08:00 | alancf | Various Clients | YES |  |
| 1130 | -07:00 | ajgraves | Linphone | YES |  |
| 1131 | -06:00 | wa5pb | Ekiga | YES |  |
| 1132 | -05:00 | tg | s60 / Blink | YES |  |
| 1133 | -07:00 | samos | Droid | YES |  |
| 1134 | -05:00 | slugmax | Grandstream GXP2000 | YES |  |
| 1135 | -08:00 | errata4q | 3cx,linphone,Blink,Ekiga | YES |  |
| 1139 | -05:00 | xcitor | Blink | YES |  |
| 1140 | +01:00 | wyan | iPad, Nexus One | YES |  |
| 1141 | -08:00 | dhaber |  | YES |  |
| 1144 | +00:00 | phm | linphone | YES |  |
| 1145 | -06:00 | xexyz | Linphone | YES |  |
| 1146 | +11:00 | thomask | Nokia E63 | YES |  |
| 1150 | +00:00 | intercal | Snom 300/various softphones | YES | YES |
| 1151 | -06:00 | jecxjo | x-lite, blackvoip | YES |  |
| 1159 | -06:00 | zeptar | Blink | YES |  |
| 1165 | -05:00 | l3vi | Linphone on IPhone 4 | YES |  |
| 1166 | -05:00 | grobe0ba | linphone on android | YES |  |
| 1169 | -06:00 | sirmxe | Various | YES |  |
| 1174 | +00:00 | nb0yjxtr | Ekiga | YES |  |
| 1177 | +00:00 | kdavis | Blink,Linphone | YES | YES |
| 1192 | -07:00 | nblade | CSipSimple on Android | YES | YES |