Physical phones have the advantage of being able to mark their own ethernet traffic with DSCP\ToS marks to classify the traffic as higher priority than normal "best effort" ethernet traffic.  For routers that support reading and prioritizing traffic based on these marks, it is the most reliable way to enable QoS for phones.


Polycom phones provisioned to our service will utilize the ToS mark 5 for both SIP and RTP audio traffic.  This can be overridden to the more modern DSCP mark per account if required.


Most all other supported phones utilize the DSCP mark AF31 (26) for SIP traffic, and EF (46) for RTP audio traffic.  This allows you to give slightly higher priority to audio traffic than SIP to prevent things like large sets of BLF updates from taking priority over an audio stream, while both have higher priority than normal best effort traffic.


Below is a reference chart of all DSCP \ Tos marks:


DSCP Class DSCP (bin) DSCP (hex) DSCP (dec) ToS (dec) ToS (hex) ToS (bin) ToS Prec. (bin) ToS Prec. (dec) ToS Delay Flag ToS Throghput Flag ToS Reliability Flag TOS String Format
none 000000 0×00 0 0 0×00 00000000 000 0 0 0 0 Routine
cs1 001000 0×08 8 32 0×20 00100000 001 1 0 0 0 Priority
af11 001010 0×0A 10 40 0×28 00101000 001 1 0 1 0 Priority
af12 001100 0×0C 12 48 0×30 00110000 001 1 1 0 0 Priority
af13 001110 0×0E 14 56 0×38 00111000 001 1 1 1 0 Priority
cs2 010000 0×10 16 64 0×40 01000000 010 2 0 0 0 Immediate
af21 010010 0×12 18 72 0×48 01001000 010 2 0 1 0 Immediate
af22 010100 0×14 20 80 0×50 01010000 010 2 1 0 0 Immediate
af23 010110 0×16 22 88 0×58 01011000 010 2 1 1 0 Immediate
cs3 011000 0×18 24 96 0×60 01100000 011 3 0 0 0 Flash
af31 011010 0×1A 26 104 0×68 01101000 011 3 0 1 0 Flash
af32 011100 0×1C 28 112 0×70 01110000 011 3 1 0 0 Flash
af33 011110 0×1E 30 120 0×78 01111000 011 3 1 1 0 Flash
cs4 100000 0×20 32 128 0×80 10000000 100 4 0 0 0 FlashOverride
af41 100010 0×22 34 136 0×88 10001000 100 4 0 1 0 FlashOverride
af42 100100 0×34 36 144 0×90 10010000 100 4 1 0 0 FlashOverride
af43 100110 0×26 38 152 0×98 10011000 100 4 1 1 0 FlashOverride
cs5 101000 0×28 40 160 0xA0 10100000 101 5 0 0 0 Critical
ef 101110 0×2E 46 184 0xB8 10111000 101 5 1 1 0 Critical
cs6 110000 0×30 48 192 0xC0 11000000 110 6 0 0 0 Internetworkcontrol
cs7 111000 0×38 56 224 0xE0 11100000 111 7 0 0 0 Networkcontrol