I've actually come across several voice (AM, FM and SSB) users of 27.7 MHz and nearby frequencies.
Yes, there is at least one Russian taxi cab company that uses 27.700 MHz FM for taxi cab dispatch. 27.70125 MHz FM is UK CB FM Channel 11. Plus there's at a handful of different paging and data link systems operating on 27.7000 MHz too.
Finland has a 5 watt on-site pager and telemetry data link service on:
27.7 MHz
27.72 MHz
27.74 MHz
27.76 MHz
27.78 MHz
27.8 MHz
27.82 MHz
27.84 MHz
27.86 MHz
27.88 MHz
27.90 MHz
27.92 MHz
27.94 MHz
Bandwidth is limited 10 kHz.
Other unknown-source POCSAG paging signals noted on 27.700 MHz as well as the "usual suspects" - freeband 11 meter CB radio traffic, most of it in SSB mode on 27.695 MHz USB, 27.700 MHz LSB, 27.700 MHz USB, 27.705 MHz LSB, and of course, AM voice comms and FM voice comms on on 27.705 MHz and 27.695 MHz and Irish churches - Parish radio (CADS / WPAS) on 27.605 MHz - 27.995 MHz and 27.60125 MHz - 27.99125 MHz. Most of the 27MHz band church broadcasts seem to be on the LW channel plan (which is identical to the UK FM CB radio band plan), with 27.70125 MHz - or 27.701 MHz being widely used.
The UW channels are just 27.605 MHz - 27.995 MHz (10 kHz spacing) so 27.705 MHz and 27.695 MHz come into play here.
Since many of these transmitters are easily 1-2 kHz off frequency, a transmitter operating on LW11 or 27.701.25 MHz or UW11, which is 27.705 MHz. being only a kHz or so off-frequency means havoc to SSTV, of course, it goes both ways.
That, and our friends the Asian fishing fleets are active on 27.700 MHz FM [CSQ]. 27.7 MHz is 480 channel FM fishery marine radio (27.5 MHz - 39.475 MHz) Channel 009. While most of the fishery chatter I've heard has been above 29, 30 MHz, they are active below 28.000 MHz.