Don't know about the Skobbler SDK, but if online query is available and you have the approximate geographical area and the name of the motorway, you may use the Overpass API (http://wiki.openstreetmap.org/wiki/Overpass_API) to query the openstreetmap database for the highway reference.
For example, the following query (for a particular bbox which contains a small section of the highway):
[out:json]
[timeout:25]
;
(
way
["highway"="motorway"]
["name"="Brooklyn-Queens Expressway"]
(40.73483602685421,-73.91463160514832,40.73785205632046,-73.9096748828888);
);
out body qt;
returns (with some key-value pairs omitted for simplicity):
{
"version": 0.6,
"generator": "Overpass API",
"osm3s": {
"timestamp_osm_base": "2015-09-18T20:21:02Z",
"copyright": "The data included in this document is from www.openstreetmap.org. The data is made available under ODbL."
},
"elements": [
{
"type": "way",
"id": 46723482,
"nodes": [
488264429,
488264444,
488264461,
488264512,
488264530,
488264541,
597315979
],
"tags": {
"bicycle": "no",
"bridge": "yes",
"foot": "no",
"hgv": "designated",
"highway": "motorway",
"horse": "no",
"lanes": "3",
"layer": "1",
"name": "Brooklyn-Queens Expressway",
"oneway": "yes",
"ref": "I 278",
"sidewalk": "none",
}
},
{
"type": "way",
"id": 46724225,
"nodes": [
597315978,
488242888,
488248526,
488248544,
488248607
],
"tags": {
"bicycle": "no",
"bridge": "yes",
"foot": "no",
"hgv": "designated",
"highway": "motorway",
"horse": "no",
"lanes": "3",
"layer": "1",
"name": "Brooklyn-Queens Expressway",
"oneway": "yes",
"ref": "I 278",
"sidewalk": "none",
}
}
]
}
Which are 2 sections of the road in the osm database. In the US the "ref" tag for interstates is in the form "I XXX" (See http://wiki.openstreetmap.org/wiki/Interstate_Highways and note the format for co-location). You can retrieve the interstate name accordingly.
You can try the above query in overpass-turbo (a UI for the service) at http://overpass-turbo.eu/s/bxi (Press RUN and the DATA tab for the returned data, and pan the map for query in another bbox).